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Kneschaurek E, Hinderhofer A, Hofferberth B, Scheffczyk N, Pithan L, Zimmermann P, Merten L, Bertram F, Schreiber F. Compact sample environment for in situ X-ray scattering during spin-coating. Rev Sci Instrum 2023; 94:063901. [PMID: 37862478 DOI: 10.1063/5.0149613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 05/14/2023] [Indexed: 10/22/2023]
Abstract
We demonstrate a compact sample environment for the in situ study of crystallization kinetics of thin films on synchrotron beamlines, featuring atmospheric control, automated deposition, spin-coating, and annealing stages. The setup is suitable for studying thin film growth in real time using grazing-incidence X-ray diffraction techniques. Humidity and oxygen levels are being detected by sensors. The spinning stage exhibits low vertical oscillation amplitude (∼3μm at speeds up to 10 000 rpm) and can optionally be employed for antisolvent application or gas quenching to investigate the impact of these techniques, which are often used to assist thin film growth. Differential reflectance spectroscopy is implemented in the spin-coater environment for inspecting thin film thickness and optical properties. The infrared radiation-based annealing system consists of a halogen lamp and a holder with an adjustable lamp-to-sample distance, while the sample surface temperature is monitored by a pyrometer. All features of the sample environment can be controlled remotely by the control software at synchrotron beamlines. In order to test and demonstrate the performance, the crystallization pathway of the antisolvent-assisted MAPbI3 (MA = methylammonium) perovskite thin film during the spinning and annealing stages is monitored and discussed.
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Affiliation(s)
| | | | - Bernd Hofferberth
- Institute of Applied Physics, University of Tübingen, 72076 Tübingen, Germany
| | - Niels Scheffczyk
- Institute of Applied Physics, University of Tübingen, 72076 Tübingen, Germany
| | - Linus Pithan
- Institute of Applied Physics, University of Tübingen, 72076 Tübingen, Germany
| | - Paul Zimmermann
- Institute of Applied Physics, University of Tübingen, 72076 Tübingen, Germany
| | - Lena Merten
- Institute of Applied Physics, University of Tübingen, 72076 Tübingen, Germany
| | - Florian Bertram
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Frank Schreiber
- Institute of Applied Physics, University of Tübingen, 72076 Tübingen, Germany
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2
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Held V, Mrkyvkova N, Nádaždy P, Vegso K, Vlk A, Ledinský M, Jergel M, Chumakov A, Roth SV, Schreiber F, Siffalovic P. Evolution of Structure and Optoelectronic Properties During Halide Perovskite Vapor Deposition. J Phys Chem Lett 2022; 13:11905-11912. [PMID: 36525260 DOI: 10.1021/acs.jpclett.2c03422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The efficiency of perovskite-based solar cells has increased dramatically over the past decade to as high as 25%, making them very attractive for commercial use. Vapor deposition is a promising technique that potentially enables fabrication of perovskite solar cells on large areas. However, to implement a large-scale deposition method, understanding and controlling the specific growth mechanisms are essential for the reproducible fabrication of high-quality layers. Here, we study the structural and optoelectronic kinetics of MAPbI3, employing in-situ photoluminescence (PL) spectroscopy and grazing-incidence small/wide-angle X-ray scattering (GI-SAXS/WAXS) simultaneously during perovskite vapor deposition. Such a unique combination of techniques reveals MAPbI3 formation from the early stages and uncovers the morphology, crystallographic structure, and defect density evolution. Furthermore, we show that the nonmonotonous character of PL intensity contrasts with the increasing volume of the perovskite phase during the growth, although bringing valuable information about the presence of defect states.
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Affiliation(s)
- Vladimir Held
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11Bratislava, Slovakia
| | - Nada Mrkyvkova
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11Bratislava, Slovakia
- Center for Advanced Materials Application, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11Bratislava, Slovakia
| | - Peter Nádaždy
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11Bratislava, Slovakia
- Center for Advanced Materials Application, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11Bratislava, Slovakia
| | - Karol Vegso
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11Bratislava, Slovakia
- Center for Advanced Materials Application, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11Bratislava, Slovakia
| | - Aleš Vlk
- Laboratory of Thin Films, Institute of Physics, ASCR, Cukrovarnická 10, 162 00Prague, Czech Republic
| | - Martin Ledinský
- Laboratory of Thin Films, Institute of Physics, ASCR, Cukrovarnická 10, 162 00Prague, Czech Republic
| | - Matej Jergel
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11Bratislava, Slovakia
- Center for Advanced Materials Application, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11Bratislava, Slovakia
| | - Andrei Chumakov
- Photon Science, Deutsches Elektronen-Synchrotron (DESY), Hamburg22607, Germany
| | - Stephan V Roth
- Photon Science, Deutsches Elektronen-Synchrotron (DESY), Hamburg22607, Germany
| | - Frank Schreiber
- Institute of Applied Physics, University of Tübingen, 72076 Tübingen, Germany
| | - Peter Siffalovic
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11Bratislava, Slovakia
- Center for Advanced Materials Application, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11Bratislava, Slovakia
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3
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Vegso K, Shaji A, Sojková M, Slušná LP, Vojteková T, Hrdá J, Halahovets Y, Hulman M, Jergel M, Majková E, Wiesmann J, Šiffalovič P. A wide-angle X-ray scattering laboratory setup for tracking phase changes of thin films in a chemical vapor deposition chamber. Rev Sci Instrum 2022; 93:113909. [PMID: 36461520 DOI: 10.1063/5.0104673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 10/19/2022] [Indexed: 06/17/2023]
Abstract
The few-layer transition metal dichalcogenides (TMD) are an attractive class of materials due to their unique and tunable electronic, optical, and chemical properties, controlled by the layer number, crystal orientation, grain size, and morphology. One of the most commonly used methods for synthesizing the few-layer TMD materials is the chemical vapor deposition (CVD) technique. Therefore, it is crucial to develop in situ inspection techniques to observe the growth of the few-layer TMD materials directly in the CVD chamber environment. We demonstrate such an in situ observation on the growth of the vertically aligned few-layer MoS2 in a one-zone CVD chamber using a laboratory table-top grazing-incidence wide-angle X-ray scattering (GIWAXS) setup. The advantages of using a microfocus X-ray source with focusing Montel optics and a single-photon counting 2D X-ray detector are discussed. Due to the position-sensitive 2D X-ray detector, the orientation of MoS2 layers can be easily distinguished. The performance of the GIWAXS setup is further improved by suppressing the background scattering using a guarding slit, an appropriately placed beamstop, and He gas in the CVD reactor. The layer growth can be monitored by tracking the width of the MoS2 diffraction peak in real time. The temporal evolution of the crystallization kinetics can be satisfactorily described by the Avrami model, employing the normalized diffraction peak area. In this way, the activation energy of the particular chemical reaction occurring in the CVD chamber can be determined.
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Affiliation(s)
- Karol Vegso
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 84511 Bratislava, Slovakia
| | - Ashin Shaji
- Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Dúbravská cesta 9/6319, 84513 Bratislava, Slovakia
| | - Michaela Sojková
- Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 84104 Bratislava, Slovakia
| | - Lenka Príbusová Slušná
- Centre for Advanced Materials Application (CEMEA), Slovak Academy of Sciences, Dúbravská cesta 5807/9, 84511 Bratislava, Slovakia
| | - Tatiana Vojteková
- Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 84104 Bratislava, Slovakia
| | - Jana Hrdá
- Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 84104 Bratislava, Slovakia
| | - Yuriy Halahovets
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 84511 Bratislava, Slovakia
| | - Martin Hulman
- Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 84104 Bratislava, Slovakia
| | - Matej Jergel
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 84511 Bratislava, Slovakia
| | - Eva Majková
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 84511 Bratislava, Slovakia
| | - Jörg Wiesmann
- Incoatec GmbH, Max-Planck-Strasse 2, 21502 Geesthacht, Germany
| | - Peter Šiffalovič
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 84511 Bratislava, Slovakia
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4
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Dull JT, Chen X, Johnson HM, Otani MC, Schreiber F, Clancy P, Rand BP. A comprehensive picture of roughness evolution in organic crystalline growth: the role of molecular aspect ratio. Mater Horiz 2022; 9:2752-2761. [PMID: 36069252 DOI: 10.1039/d2mh00854h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Exploiting the capabilities of organic semiconductors for applications ranging from light-emitting diodes to photovoltaics to lasers relies on the creation of ordered, smooth layers for optimal charge carrier mobilities and exciton diffusion. This, in turn, creates a demand for organic small molecules that can form smooth thin film crystals via homoepitaxy. We have studied a set of small-molecule organic semiconductors that serve as templates for homoepitaxy. The surface roughness of these materials is measured as a function of adlayer film thickness from which the growth exponent (β) is extracted. Notably, we find that three-dimensional molecules that have low molecular aspect ratios (AR) tend to remain smooth as thickness increases (small β). This is in contrast to planar or rod-like molecules with high AR that quickly roughen (large β). Molecular dynamics simulations find that the Ehrlich-Schwöbel barrier (EES) alone is unable to fully explain this trend. We further investigated the mobility of ad-molecules on the crystalline surface to categorize their diffusion behaviors and the effects of aggregation to account for the different degrees of roughness that we observed. Our results suggest that low AR molecules have low molecular mobility and moderate EES which creates a downward funneling effect leading to smooth crystal growth.
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Affiliation(s)
- Jordan T Dull
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA.
| | - Xiangyu Chen
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Holly M Johnson
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA.
| | - Maria Clara Otani
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA.
| | - Frank Schreiber
- Institute for Applied Physics, University of Tubingen, 72076 Tubingen, Germany
| | - Paulette Clancy
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Barry P Rand
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA.
- Andlinger Center for Energy and the Environment, Princeton University, Princeton, NJ 08544, USA
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5
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Mareček D, Oberreiter J, Nelson A, Kowarik S. Faster and lower-dose X-ray reflectivity measurements enabled by physics-informed modeling and artificial intelligence co-refinement. J Appl Crystallogr 2022; 55:1305-1313. [PMID: 36249496 PMCID: PMC9533750 DOI: 10.1107/s2053273322008051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 08/11/2022] [Indexed: 11/10/2022] Open
Abstract
An approach is presented for analysis of real-time X-ray reflectivity (XRR) process data not just as a function of the magnitude of the reciprocal-space vector q, as is commonly done, but as a function of both q and time. The real-space structures extracted from the XRR curves are restricted to be solutions of a physics-informed growth model and use state-of-the-art convolutional neural networks (CNNs) and differential evolution fitting to co-refine multiple time-dependent XRR curves R(q, t) of a thin film growth experiment. Thereby it becomes possible to correctly analyze XRR data with a fidelity corresponding to standard fits of individual XRR curves, even if they are sparsely sampled, with a sevenfold reduction of XRR data points, or if the data are noisy due to a 200-fold reduction in counting times. The approach of using a CNN analysis and of including prior information through a kinetic model is not limited to growth studies but can be easily extended to other kinetic X-ray or neutron reflectivity data to enable faster measurements with less beam damage.
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Affiliation(s)
- David Mareček
- Physikalische und Theoretische Chemie, Universität Graz, Heinrichstraße 28, Graz, 8010, Austria
| | - Julian Oberreiter
- Physikalische und Theoretische Chemie, Universität Graz, Heinrichstraße 28, Graz, 8010, Austria
| | - Andrew Nelson
- ANSTO, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Stefan Kowarik
- Physikalische und Theoretische Chemie, Universität Graz, Heinrichstraße 28, Graz, 8010, Austria,Correspondence e-mail:
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6
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Mareček D, Oberreiter J, Nelson A, Kowarik S. Faster and lower-dose X-ray reflectivity measurements enabled by physics-informed modeling and artificial intelligence co-refinement. J Appl Crystallogr 2022. [DOI: 10.1107/s1600576722008056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
An approach is presented for analysis of real-time X-ray reflectivity (XRR) process data not just as a function of the magnitude of the reciprocal-space vector q, as is commonly done, but as a function of both q and time. The real-space structures extracted from the XRR curves are restricted to be solutions of a physics-informed growth model and use state-of-the-art convolutional neural networks (CNNs) and differential evolution fitting to co-refine multiple time-dependent XRR curves R(q, t) of a thin film growth experiment. Thereby it becomes possible to correctly analyze XRR data with a fidelity corresponding to standard fits of individual XRR curves, even if they are sparsely sampled, with a sevenfold reduction of XRR data points, or if the data are noisy due to a 200-fold reduction in counting times. The approach of using a CNN analysis and of including prior information through a kinetic model is not limited to growth studies but can be easily extended to other kinetic X-ray or neutron reflectivity data to enable faster measurements with less beam damage.
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7
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Mondal M, Ganapathy R. Direct Measurements of Surface Strain-Mediated Lateral Interactions between Adsorbates in Colloidal Heteroepitaxy. Phys Rev Lett 2022; 129:088003. [PMID: 36053694 DOI: 10.1103/physrevlett.129.088003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/10/2022] [Accepted: 07/05/2022] [Indexed: 06/15/2023]
Abstract
Surface strain can alter the dynamics of adsorbates, and often, the adsorbates themselves induce and interact via their surface strain fields. In epitaxy, such strain-mediated effects get further compounded when a misfit strain exists due to lattice mismatch between the growing film and substrate. Here, we carry out particle-resolved imaging of heteroepitaxial growth of multilayer colloidal films where the particles interact via a short-range attraction. Surprisingly, although the misfit strain relaxed systematically with film thickness, the adcolloid diffusivity was nonmonotonic. We show that this nonmonotonicity stems from the competition between the spatial extent of self-induced in-layer strain and the short interaction range. Importantly, we provide direct evidence for long-ranged strain-mediated interactions between adsorbates and show that it alters the growing film's morphology.
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Affiliation(s)
- Manodeep Mondal
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560064, India
| | - Rajesh Ganapathy
- International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560064, India
- School of Advanced Materials (SAMat), Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560064, India
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8
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Despoja V, Marušić L. Prediction of Strong Transversal s(TE) Exciton–Polaritons in C60 Thin Crystalline Films. Int J Mol Sci 2022; 23:6943. [PMID: 35805945 PMCID: PMC9266707 DOI: 10.3390/ijms23136943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/20/2022] [Accepted: 06/20/2022] [Indexed: 12/10/2022] Open
Abstract
If an exciton and a photon can change each other’s properties, indicating that the regime of their strong bond is achieved, it usually happens in standard microcavity devices, where the large overlap between the ’confined’ cavity photons and the 2D excitons enable the hybridization and the band gap opening in the parabolic photonic branch (as clear evidence of the strong exciton–photon coupling). Here, we show that the strong light–matter coupling can occur beyond the microcavity device setup, i.e., between the ’free’ s(TE) photons and excitons. The s(TE) exciton–polariton is a polarization mode, which (contrary to the p(TM) mode) appears only as a coexistence of a photon and an exciton, i.e., it vanishes in the non-retarded limit (c→∞). We show that a thin fullerene C60 crystalline film (consisting of N C60 single layers) deposited on an Al2O3 dielectric surface supports strong evanescent s(TE)-polarized exciton–polariton. The calculated Rabi splitting is more than Ω=500 meV for N=10, with a tendency to increase with N, indicating a very strong photonic character of the exciton–polariton.
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9
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Abstract
Kinetic Monte Carlo simulations of a model of thin film heteroepitaxy are performed to investigate the effects of the deposition temperature in the initial growth stages. Broad ranges of the rates of surface processes are used to model materials with several activation energies and several temperature changes, in conditions of larger diffusivity on the substrate in comparison with other film layers. When films with the same coverage are compared, the roughness increases with the deposition temperature in the regimes of island growth, coalescence, and initial formation of the continuous films. Concomitantly, the position of the minimum of the autocorrelation function is displaced to larger sizes. These apparently universal trends are consequences of the formation of wider and taller islands, and are observed with or without Ehrlich-Schwöebel barriers for adatom diffusion at step edges. The roughness increase with temperature qualitatively matches the observations of recent works on the deposition of inorganic and organic materials. In thicker films, simulations with some parameter sets show the decrease of roughness with temperature. In these cases, a re-entrance of roughness may be observed in the initial formation of the continuous films.
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10
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Empting E, Bader N, Oettel M. Interplay of orientational order and roughness in simulated thin film growth of anisotropically interacting particles. Phys Rev E 2022; 105:045306. [PMID: 35590594 DOI: 10.1103/physreve.105.045306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 03/29/2022] [Indexed: 06/15/2023]
Abstract
Roughness and orientational order in thin films of anisotropic particles are investigated using kinetic Monte Carlo simulations on a cubic lattice. Anisotropic next-neighbor interactions between the lattice particles were chosen to mimic the effects of shape anisotropy in the interactions of disk- or rodlike molecules with van der Waals attractions. Increasing anisotropy leads first to a preferred orientation in the film (which is close to the corresponding equilibrium transition) while the qualitative mode of roughness evolution (known from isotropic systems) does not change. At strong anisotropies, an effective step-edge (Ehrlich-Schwoebel) barrier appears and a nonequilibrium roughening effect is found, accompanied by reordering in the film which can be interpreted as the nucleation and growth of domains of lying-down disks or rods. The information on order and roughness is combined into a diagram of dynamic growth modes.
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Affiliation(s)
- E Empting
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - N Bader
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - M Oettel
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
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11
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Li H, Roth SV, Freychet G, Zhernenkov M, Asta N, Wågberg L, Pettersson T. Structure Development of the Interphase between Drying Cellulose Materials Revealed by In Situ Grazing-Incidence Small-Angle X-ray Scattering. Biomacromolecules 2021; 22:4274-4283. [PMID: 34541856 PMCID: PMC8512666 DOI: 10.1021/acs.biomac.1c00845] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 09/07/2021] [Indexed: 11/29/2022]
Abstract
The nano- to microscale structures at the interface between materials can define the macroscopic material properties. These structures are extremely difficult to investigate for complex material systems, such as cellulose-rich materials. The development of new model cellulose materials and measuring techniques has opened new possibilities to resolve this problem. We present a straightforward approach combining micro-focusing grazing-incidence small-angle X-ray scattering and atomic force microscopy (AFM) to investigate the structural rearrangements of cellulose/cellulose interfaces in situ during drying. Based on the results, we propose that molecular interdiffusion and structural rearrangement play a major role in the development of the properties of the cellulose/cellulose interphase; this model is representative of the development of the properties of joint/contact points between macroscopic cellulose fibers.
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Affiliation(s)
- Hailong Li
- Department
of Fibre and Polymer Technology, KTH Royal
Institute of Technology, Teknikringen 58, SE-100 44 Stockholm, Sweden
- Department
of Physics, AlbaNova University Center, Stockholm University, Stockholm 10691, Sweden
| | - Stephan V. Roth
- Deutsches
Elektronen-Synchrotron (DESY), Notkestr. 85, Hamburg 22607, Germany
| | - Guillaume Freychet
- National
Synchrotron Light Source II, Brookhaven
National Laboratory, Upton, New York 11973, United States
| | - Mikhail Zhernenkov
- National
Synchrotron Light Source II, Brookhaven
National Laboratory, Upton, New York 11973, United States
| | - Nadia Asta
- Department
of Fibre and Polymer Technology, KTH Royal
Institute of Technology, Teknikringen 58, SE-100 44 Stockholm, Sweden
| | - Lars Wågberg
- Department
of Fibre and Polymer Technology, KTH Royal
Institute of Technology, Teknikringen 58, SE-100 44 Stockholm, Sweden
- Wallenberg
Wood Science Centre, Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 56, Stockholm 10044, Sweden
| | - Torbjörn Pettersson
- Department
of Fibre and Polymer Technology, KTH Royal
Institute of Technology, Teknikringen 58, SE-100 44 Stockholm, Sweden
- Wallenberg
Wood Science Centre, Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 56, Stockholm 10044, Sweden
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12
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Abstract
Morphologies of adsorbed molecular films are of interest in a wide range of applications. To study the epitaxial growth of these systems in computer simulations requires access to long time and length scales, and one typically resorts to kinetic Monte Carlo (KMC) simulations. However, KMC simulations require as input transition rates and their dependence on external parameters (such as temperature). Experimental data allow only limited and indirect access to these rates, and models are often oversimplified. Here, we follow a bottom-up approach and aim at systematically constructing all relevant rates for an example system that has shown interesting properties in experiments, buckminsterfullerene on a calcium fluoride substrate. We develop classical force fields (both atomistic and coarse-grained) and perform molecular dynamics simulations of the elementary transitions in order to derive explicit expressions for the transition rates with a minimal number of free parameters.
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Affiliation(s)
- William Janke
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
| | - Thomas Speck
- Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7-9, 55128 Mainz, Germany
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13
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Empting E, Klopotek M, Hinderhofer A, Schreiber F, Oettel M. Lattice gas study of thin-film growth scenarios and transitions between them: Role of substrate. Phys Rev E 2021; 103:023302. [PMID: 33736115 DOI: 10.1103/physreve.103.023302] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 01/17/2021] [Indexed: 11/07/2022]
Abstract
Thin-film growth is investigated in two types of lattice gas models where substrate and film particles are different, expressed by unequal interaction energy parameters. The first is of solid-on-solid type, whereas the second additionally incorporates desorption, diffusion in the gas phase above the film and readsorption at the film (appropriate for growth in colloidal systems). In both models, the difference between particle-substrate and particle-particle interactions plays a central role for the evolution of the film morphology at intermediate times. The models exhibit a dynamic layering transition which occurs at generally lower substrate attraction strengths than the equilibrium layering transition. A second, flattening transition is found where initial island growth transforms to layer-by-layer growth at intermediate deposition times. Combined with the known roughening behavior in such models for very large deposition times, we present four global growth scenarios, charting out the possible types of roughness evolution.
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Affiliation(s)
- E Empting
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
| | - M Klopotek
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
| | - A Hinderhofer
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
| | - F Schreiber
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
| | - M Oettel
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
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14
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Duva G, Pithan L, Gerlach A, Janik A, Hinderhofer A, Schreiber F. Roughness evolution in strongly interacting donor:acceptor mixtures of molecular semiconductors. An in situ, real-time growth study using x-ray reflectivity. J Phys Condens Matter 2021; 33:115003. [PMID: 33285533 DOI: 10.1088/1361-648x/abd11c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The evolution of surface roughness in binary mixtures of the two molecular organic semiconductors (OSCs) diindenoperylene (DIP) as electron-donor and 1, 3, 4, 5, 7, 8-hexafluoro-tetracyano naphthoquinodimethane (F6TCNNQ) as electron-acceptor is studied. We co-deposit DIP and F6TCNNQ in vacuum with varying relative molar content while keeping a molar excess of DIP in order to produce phase-heterogeneous mixtures. The excess DIP phase segregates in pristine crystallites, whereas the remaining mixed phase is constituted by DIP:F6TCNNQ co-crystallites. We calculate the surface roughness as function of film thickness by modelling x-ray reflectivity data acquired in situ and in real-time during film growth. To model the experimental data, two distinct approaches, namely the kinematic approximation and the Parratt formalism, are applied. A comparative study of surface roughness evolution as function of DIP:F6TCNNQ mixing ratio is carried out implementing the Trofimov growth model within the kinematic approximation. Depending on the thickness regime, mixing ratio-specific trends are identified and discussed. To explain them, a growth mechanism for binary heterogeneous mixtures of strongly interacting OSCs is proposed.
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Affiliation(s)
- G Duva
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - L Pithan
- ESRF - The European Synchrotron, 71, Avenue des Martyrs, 38000 Grenoble, France
| | - A Gerlach
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - A Janik
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - A Hinderhofer
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - F Schreiber
- University of Tübingen, Institute for Applied Physics, Auf der Morgenstelle 10, 72076 Tübingen, Germany
- Center for Light-Matter Interactions, Sensors and Analytics (LISA+), Auf der Morgenstelle 15, 72076 Tübingen, Germany
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15
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Abstract
The quantitative role of entropy in the surface diffusion of molecules with many degrees of freedom is still not well understood. Here, we quantify entropic diffusion barriers as well as attempt frequencies by performing a systematic decomposition of the Arrhenius equation for single oligophenyl molecules of various lengths (two to six phenyl rings and benzene as the reference) on an amorphous silica surface using extensive molecular dynamics simulations. Attempt frequencies evaluated from velocity auto-correlation functions are found close to kBT/h, the frequency factor of transition state theory. Importantly, we find large positive entropy contributions to the free energy barrier of diffusion up to 55%, increasing with molecular length with 4.1 kJ/mol/phenyl ring. The entropic barrier is about 40%-60% of the entropy of the molecule surface adsorption free energy, revealing that at the transition states, the molecules can liberate a major part of their conformational states, increasing with length. The substantial role of the internal degrees of freedom for the diffusive dynamics is explicitly demonstrated by studying internally constrained, "rigid" version of the molecules. Finally, we discuss also rotational diffusion and the role of surface vibrations. Our results affirm that it is essential for quantitative studies and interpretation of surface diffusion of complex molecules to consider internal entropic effects.
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Affiliation(s)
- Mila Miletic
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Karol Palczynski
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany
| | - Joachim Dzubiella
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany
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16
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Luis EEM, Carrasco ISS, de Assis TA, Reis FDAA. Statistics of adatom diffusion in a model of thin film growth. Phys Rev E 2020; 102:012805. [PMID: 32794924 DOI: 10.1103/physreve.102.012805] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 06/30/2020] [Indexed: 11/07/2022]
Abstract
We study the statistics of the number of executed hops of adatoms at the surface of films grown with the Clarke-Vvedensky (CV) model in simple cubic lattices. The distributions of this number N are determined in films with average thicknesses close to 50 and 100 monolayers for a broad range of values of the diffusion-to-deposition ratio R and of the probability ε that lowers the diffusion coefficient for each lateral neighbor. The mobility of subsurface atoms and the energy barriers for crossing step edges are neglected. Simulations show that the adatoms execute uncorrelated diffusion during the time in which they move on the film surface. In a low temperature regime, typically with Rε≲1, the attachment to lateral neighbors is almost irreversible, the average number of hops scales as 〈N〉∼R^{0.38±0.01}, and the distribution of that number decays approximately as exp[-(N/〈N〉)^{0.80±0.07}]. Similar decay is observed in simulations of random walks in a plane with randomly distributed absorbing traps and the estimated relation between 〈N〉 and the density of terrace steps is similar to that observed in the trapping problem, which provides a conceptual explanation of that regime. As the temperature increases, 〈N〉 crosses over to another regime when Rε^{3.0±0.3}∼1, which indicates high mobility of all adatoms at terrace borders. The distributions P(N) change to simple exponential decays, due to the constant probability for an adatom to become immobile after being covered by a new deposited layer. At higher temperatures, the surfaces become very smooth and 〈N〉∼Rε^{1.85±0.15}, which is explained by an analogy with submonolayer growth. Thus, the statistics of adatom hops on growing film surfaces is related to universal and nonuniversal features of the growth model and with properties of trapping models if the hopping time is limited by the landscape and not by the deposition of other layers.
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Affiliation(s)
- Edwin E Mozo Luis
- Instituto de Física, Universidade Federal da Bahia, Campus Universitário da Federação, Rua Barão de Jeremoabo s/n, 40170-115 Salvador, Bahia, Brazil
| | - Ismael S S Carrasco
- Instituto de Física, Universidade Federal Fluminense, Avenida Litorânea s/n, 24210-340 Niterói, Rio de Janeiro, Brazil
| | - Thiago A de Assis
- Instituto de Física, Universidade Federal da Bahia, Campus Universitário da Federação, Rua Barão de Jeremoabo s/n, 40170-115 Salvador, Bahia, Brazil
| | - Fábio D A Aarão Reis
- Instituto de Física, Universidade Federal Fluminense, Avenida Litorânea s/n, 24210-340 Niterói, Rio de Janeiro, Brazil
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17
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Huss-Hansen MK, Hodas M, Mrkyvkova N, Hagara J, Jensen BBE, Osadnik A, Lützen A, Majková E, Siffalovic P, Schreiber F, Tavares L, Kjelstrup-Hansen J, Knaapila M. Surface-Controlled Crystal Alignment of Naphthyl End-Capped Oligothiophene on Graphene: Thin-Film Growth Studied by in Situ X-ray Diffraction. Langmuir 2020; 36:1898-1906. [PMID: 32027509 DOI: 10.1021/acs.langmuir.9b03467] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report on the microstructure, morphology, and growth of 5,5'-bis(naphth-2-yl)-2,2'-bithiophene (NaT2) thin films deposited on graphene, characterized by grazing incidence X-ray diffraction (GIXRD) and complemented by atomic force microscopy (AFM) measurements. NaT2 is deposited on two types of graphene surfaces: custom-made samples where chemical vapor deposition (CVD)-grown graphene layers are transferred onto a Si/SiO2 substrate by us and common commercially transferred CVD graphene on Si/SiO2. Pristine Si/SiO2 substrates are used as a reference. The NaT2 crystal structure and orientation depend strongly on the underlying surface, with the molecules predominantly lying down on the graphene surface (face-on orientation) and standing nearly out-of-plane (edge-on orientation) on the Si/SiO2 reference surface. Post growth GIXRD and AFM measurements reveal that the crystalline structure and grain morphology differ depending on whether there is polymer residue left on the graphene surface. In situ GIXRD measurements show that the thickness dependence of the intensity of the (111) reflection from the crystalline edge-on phase does not intersect zero at the beginning of the deposition process, suggesting that an initial wetting layer, corresponding to 1-2 molecular layers, is formed at the surface-film interface. By contrast, the (111) reflection intensity from the crystalline face-on phase grows at a constant rate as a function of film thickness during the entire deposition.
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Affiliation(s)
| | - Martin Hodas
- Institut für Angewandte Physik, Universität Tübingen, Tübingen 72076, Germany
| | - Nada Mrkyvkova
- Institute of Physics, Slovak Academy of Sciences, Bratislava 84511, Slovakia
- Centre of Excellence for Advanced Materials Application, Bratislava 84511, Slovakia
| | - Jakub Hagara
- Institute of Physics, Slovak Academy of Sciences, Bratislava 84511, Slovakia
- Centre of Excellence for Advanced Materials Application, Bratislava 84511, Slovakia
| | | | - Andreas Osadnik
- Kekulé-Institute for Organic Chemistry and Biochemistry, University of Bonn, Bonn 53121, Germany
| | - Arne Lützen
- Kekulé-Institute for Organic Chemistry and Biochemistry, University of Bonn, Bonn 53121, Germany
| | - Eva Majková
- Institute of Physics, Slovak Academy of Sciences, Bratislava 84511, Slovakia
- Centre of Excellence for Advanced Materials Application, Bratislava 84511, Slovakia
| | - Peter Siffalovic
- Institute of Physics, Slovak Academy of Sciences, Bratislava 84511, Slovakia
- Centre of Excellence for Advanced Materials Application, Bratislava 84511, Slovakia
| | - Frank Schreiber
- Institut für Angewandte Physik, Universität Tübingen, Tübingen 72076, Germany
| | - Luciana Tavares
- NanoSYD, Mads Clausen Institute, University of Southern Denmark, Sønderborg 6400, Denmark
| | - Jakob Kjelstrup-Hansen
- NanoSYD, Mads Clausen Institute, University of Southern Denmark, Sønderborg 6400, Denmark
| | - Matti Knaapila
- Department of Physics, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
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18
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Nguyen NN, Lee HC, Yoo MS, Lee E, Lee H, Lee SB, Cho K. Charge-Transfer-Controlled Growth of Organic Semiconductor Crystals on Graphene. Adv Sci (Weinh) 2020; 7:1902315. [PMID: 32195079 PMCID: PMC7080519 DOI: 10.1002/advs.201902315] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 11/09/2019] [Indexed: 06/10/2023]
Abstract
Controlling the growth behavior of organic semiconductors (OSCs) is essential because it determines their optoelectronic properties. In order to accomplish this, graphene templates with electronic-state tunability are used to affect the growth of OSCs by controlling the van der Waals interaction between OSC ad-molecules and graphene. However, in many graphene-molecule systems, the charge transfer between an ad-molecule and a graphene template causes another important interaction. This charge-transfer-induced interaction is never considered in the growth scheme of OSCs. Here, the effects of charge transfer on the formation of graphene-OSC heterostructures are investigated, using fullerene (C60) as a model compound. By in situ electrical doping of a graphene template to suppress the charge transfer between C60 ad-molecules and graphene, the layer-by-layer growth of a C60 film on graphene can be achieved. Under this condition, the graphene-C60 interface is free of Fermi-level pinning; thus, barristors fabricated on the graphene-C60 interface show a nearly ideal Schottky-Mott limit with efficient modulation of the charge-injection barrier. Moreover, the optimized C60 film exhibits a high field-effect electron mobility of 2.5 cm2 V-1 s-1. These results provide an efficient route to engineering highly efficient optoelectronic graphene-OSC hybrid material applications.
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Affiliation(s)
- Nguyen Ngan Nguyen
- Department of Chemical EngineeringPohang University of Science and TechnologyPohang37673Republic of Korea
| | - Hyo Chan Lee
- Department of Chemical EngineeringPohang University of Science and TechnologyPohang37673Republic of Korea
| | - Min Seok Yoo
- Department of Chemical EngineeringPohang University of Science and TechnologyPohang37673Republic of Korea
| | - Eunho Lee
- Department of Chemical EngineeringPohang University of Science and TechnologyPohang37673Republic of Korea
| | - Hansol Lee
- Department of Chemical EngineeringPohang University of Science and TechnologyPohang37673Republic of Korea
| | - Seon Baek Lee
- Department of Chemical EngineeringPohang University of Science and TechnologyPohang37673Republic of Korea
| | - Kilwon Cho
- Department of Chemical EngineeringPohang University of Science and TechnologyPohang37673Republic of Korea
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19
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Mondal M, Mishra CK, Banerjee R, Narasimhan S, Sood AK, Ganapathy R. Cooperative particle rearrangements facilitate the self-organized growth of colloidal crystal arrays on strain-relief patterns. Sci Adv 2020; 6:eaay8418. [PMID: 32181352 PMCID: PMC7056312 DOI: 10.1126/sciadv.aay8418] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 12/11/2019] [Indexed: 06/10/2023]
Abstract
Strain-relief pattern formation in heteroepitaxy is well understood for particles with long-range attraction and is a routinely exploited organizational principle for atoms and molecules. However, for particles with short-range attraction such as colloids and nanoparticles, which form brittle assemblies, the mechanism(s) of strain-relief is not known. Here, we found that for colloids with short-range attraction, monolayer films on substrates with square symmetry could accommodate large compressive misfit strains through locally dewetted hexagonally ordered stripes. Unexpectedly, over a window of compressive strains, cooperative particle rearrangements first resulted in a periodic strain-relief pattern, which then guided the growth of laterally ordered defect-free colloidal crystals. Particle-resolved imaging of monomer dynamics on strained substrates also helped uncover cooperative kinetic pathways for surface transport. These processes, which substantially influenced the film morphology, have remained unobserved in atomic heteroepitaxy studies hitherto. Leaning on our findings, we developed a heteroepitaxy approach for fabricating hierarchically ordered surface structures.
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Affiliation(s)
- Manodeep Mondal
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
- School of Advanced Materials (SAMat), Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Chandan K. Mishra
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Rajdeep Banerjee
- School of Advanced Materials (SAMat), Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Shobhana Narasimhan
- School of Advanced Materials (SAMat), Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
- Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - A. K. Sood
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
- International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Rajesh Ganapathy
- School of Advanced Materials (SAMat), Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
- International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
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20
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Martynec T, Klapp SHL. Modeling of nonequilibrium surface growth by a limited-mobility model with distributed diffusion length. Phys Rev E 2019; 100:033307. [PMID: 31639962 DOI: 10.1103/physreve.100.033307] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Indexed: 11/07/2022]
Abstract
Kinetic Monte Carlo (KMC) simulations are a well-established numerical tool to investigate the time-dependent surface morphology in molecular beam epitaxy experiments. In parallel, simplified approaches such as limited mobility (LM) models characterized by a fixed diffusion length have been studied. Here we investigate an extended LM model to gain deeper insight into the role of diffusional processes concerning the growth morphology. Our model is based on the stochastic transition rules of the Das Sarma-Tamborena model but differs from the latter via a variable diffusion length. A first guess for this length can be extracted from the saturation value of the mean-squared displacement calculated from short KMC simulations. Comparing the resulting surface morphologies in the sub- and multilayer growth regime to those obtained from KMC simulations, we find deviations which can be cured by adding fluctuations to the diffusion length. This mimics the stochastic nature of particle diffusion on a substrate, an aspect which is usually neglected in LM models. We propose to add fluctuations to the diffusion length by choosing this quantity for each adsorbed particle from a Gaussian distribution, where the variance of the distribution serves as a fitting parameter. We show that the diffusional fluctuations have a huge impact on cluster properties during submonolayer growth as well as on the surface profile in the high coverage regime. The analysis of the surface morphologies on one- and two-dimensional substrates during sub- and multilayer growth shows that the LM model can produce structures that are indistinguishable to the ones from KMC simulations at arbitrary growth conditions.
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Affiliation(s)
- Thomas Martynec
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
| | - Sabine H L Klapp
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
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21
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Huttner A, Breuer T, Witte G. Controlling Interface Morphology and Layer Crystallinity in Organic Heterostructures: Microscopic View on C 60 Island Formation on Pentacene Buffer Layers. ACS Appl Mater Interfaces 2019; 11:35177-35184. [PMID: 31455082 DOI: 10.1021/acsami.9b09369] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Controlling the crystallinity of organic thin films is an important aspect in the improvement of organic electronic devices. However, because of high molecular mass, structural anisotropy, and weak intermolecular van der Waals bonding, crystalline ordering is not easily accomplished. While film preparation at elevated substrate temperature often improves the crystalline quality, this approach cannot be applied to temperature-sensitive materials such as plastic foils used as substrates for flexible electronics. Here, we examine in detail a low-temperature approach to improve film crystallinity by using ultrathin pentacene (PEN) buffer layers that allow crystalline growth of buckminsterfullerene (C60) thin films while without such buffer layers, only amorphous fullerene films are formed upon room-temperature deposition on various support substrates. Remarkably, this effect depends critically on the thickness of the PEN buffer and requires a thickness of at least two monolayers to induce crystalline growth, whereas a buffer layer consisting of a monolayer of PEN again yields amorphous C60 films. Combining crystallographic investigations by X-ray diffraction and atomic force microscopy measurements, we determine distinct nucleation sites on buffer layers of different thickness, which are correlated to the amorphous, respectively crystalline C60 islands. Our microscopic analysis reveals distinct differences for the nucleation and diffusivity of fullerenes on the PEN monolayer and on thicker buffer layers, which are attributed to the molecular arrangement in the PEN monolayer. Finally, we show that the crystalline C60 films are exclusively (111)-oriented and the fullerene islands are even heteroepitaxially aligned on the PEN buffer.
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Affiliation(s)
- Andrea Huttner
- Fachbereich Physik , Philipps-Universität Marburg , 35032 Marburg , Germany
| | - Tobias Breuer
- Fachbereich Physik , Philipps-Universität Marburg , 35032 Marburg , Germany
| | - Gregor Witte
- Fachbereich Physik , Philipps-Universität Marburg , 35032 Marburg , Germany
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22
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Headrick RL, Ulbrandt JG, Myint P, Wan J, Li Y, Fluerasu A, Zhang Y, Wiegart L, Ludwig KF. Coherent X-ray measurement of step-flow propagation during growth on polycrystalline thin film surfaces. Nat Commun 2019; 10:2638. [PMID: 31201329 PMCID: PMC6570654 DOI: 10.1038/s41467-019-10629-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 05/14/2019] [Indexed: 11/09/2022] Open
Abstract
The properties of artificially grown thin films are strongly affected by surface processes during growth. Coherent X-rays provide an approach to better understand such processes and fluctuations far from equilibrium. Here we report results for vacuum deposition of C60 on a graphene-coated surface investigated with X-ray Photon Correlation Spectroscopy in surface-sensitive conditions. Step-flow is observed through measurement of the step-edge velocity in the late stages of growth after crystalline mounds have formed. We show that the step-edge velocity is coupled to the terrace length, and that there is a variation in the velocity from larger step spacing at the center of crystalline mounds to closely-spaced, more slowly propagating steps at their edges. The results extend theories of surface growth, since the behavior is consistent with surface evolution driven by processes that include surface diffusion, the motion of step-edges, and attachment at step edges with significant step-edge barriers.
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Affiliation(s)
- Randall L Headrick
- Department of Physics and Materials Science Program, University of Vermont, Burlington, VT, 05405, USA.
| | - Jeffrey G Ulbrandt
- Department of Physics and Materials Science Program, University of Vermont, Burlington, VT, 05405, USA
| | - Peco Myint
- Division of Materials Science and Engineering, Boston University, Boston, MA, 02215, USA
| | - Jing Wan
- Department of Physics and Materials Science Program, University of Vermont, Burlington, VT, 05405, USA
| | - Yang Li
- Department of Physics and Materials Science Program, University of Vermont, Burlington, VT, 05405, USA
| | | | - Yugang Zhang
- National Synchrotron Light Source II, Upton, NY, 11967, USA
| | - Lutz Wiegart
- National Synchrotron Light Source II, Upton, NY, 11967, USA
| | - Karl F Ludwig
- Division of Materials Science and Engineering, Boston University, Boston, MA, 02215, USA.,Department of Physics, Boston University, Boston, MA, 02215, USA
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23
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Abstract
By means of computer simulations and kinetic rate equations, we study the formation of a film of rod-like particles which are deposited on a substrate. The rod-rod interactions are hard with a short-range attraction of variable strength and width, and the rod-substrate interactions favor lying rods with a variable strength. For a rod aspect ratio of 5 and deposition of up to an equivalent of one monolayer of standing rods, we demonstrate a rich variety of growth modes upon variation of the three interaction parameters. We formulate rate equations for the time evolution of densities of islands composed of standing, lying, and mixed rods. Input parameters such as diffusion constants, island capture numbers, and rod reorientation free energies are extracted from simulations, while rod reorientation attempt frequencies remain as free parameters. Numerical solutions of the rate equations in a simple truncation show rough qualitative agreement with the simulations for the early stage of film growth but an extension to later stages requires to go significantly beyond this simple truncation.
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Affiliation(s)
- M Dixit
- Université du Luxembourg, Theory of Soft Condensed Matter, Physics and Materials Sciences Research Unit, L-1511 Luxembourg, Luxembourg
| | - T Schilling
- Physikalisches Institut, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
| | - M Oettel
- Institut für Angewandte Physik, Eberhard Karls Universität Tübingen, D-72076 Tübingen, Germany
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24
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Abstract
The shape of individual building blocks is an important parameter in bottom-up self-assembly of nanostructured materials. A simple shape change from sphere to spheroid can significantly affect the assembly process due to the modification to the orientational degrees of freedom. When a layer of spheres is placed upon a layer of spheroids, the strain at the interface can be minimized by the spheroid taking a special orientation. C70 fullerenes represent the smallest spheroids, and their interaction with a sphere-like C60 is investigated. We find that the orientation of the C70 within a close-packed C70 layer can be steered by contacting a layer of C60. This orientational steering phenomenon is potentially useful for epitaxial growth of multilayer van der Waals molecular heterostructures.
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Affiliation(s)
- Lu'an Guo
- Department of Applied Physics and Key Laboratory for Quantum Information and Quantum Optoelectronic Devices of Shaanxi Province , Xi'an Jiaotong University , Xi'an 710049 , China
- School of Physics and Astronomy , University of Birmingham , Edgbaston, Birmingham B15 2TT , U.K
| | - Yitao Wang
- School of Physics and Astronomy , University of Birmingham , Edgbaston, Birmingham B15 2TT , U.K
| | - Dogan Kaya
- Department of Electronics and Automation, Vocational School of Adana , Cukurova University , 01160 Cukurova , Adana , Turkey
| | - Richard E Palmer
- College of Engineering , Swansea University , Bay Campus, Fabian Way , Swansea SA1 8EN , U.K
| | - Guangde Chen
- Department of Applied Physics and Key Laboratory for Quantum Information and Quantum Optoelectronic Devices of Shaanxi Province , Xi'an Jiaotong University , Xi'an 710049 , China
| | - Quanmin Guo
- School of Physics and Astronomy , University of Birmingham , Edgbaston, Birmingham B15 2TT , U.K
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25
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Maaß F, Jiang Y, Liu W, Tkatchenko A, Tegeder P. Binding energies of benzene on coinage metal surfaces: Equal stability on different metals. J Chem Phys 2018; 148:214703. [DOI: 10.1063/1.5030094] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Friedrich Maaß
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Yingda Jiang
- Nano Structural Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu, China
| | - Wei Liu
- Nano Structural Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu, China
| | - Alexandre Tkatchenko
- Physics and Materials Science Research Unit, University of Luxembourg, L-1511 Luxembourg, Luxembourg
| | - Petra Tegeder
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
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26
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Janneck R, Pilet N, Bommanaboyena SP, Watts B, Heremans P, Genoe J, Rolin C. Highly Crystalline C8-BTBT Thin-Film Transistors by Lateral Homo-Epitaxial Growth on Printed Templates. Adv Mater 2017; 29:1703864. [PMID: 29024126 DOI: 10.1002/adma.201703864] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 08/25/2017] [Indexed: 06/07/2023]
Abstract
Highly crystalline thin films of organic semiconductors offer great potential for fundamental material studies as well as for realizing high-performance, low-cost flexible electronics. The fabrication of these films directly on inert substrates is typically done by meniscus-guided coating techniques. The resulting layers show morphological defects that hinder charge transport and induce large device-to-device variability. Here, a double-step method for organic semiconductor layers combining a solution-processed templating layer and a lateral homo-epitaxial growth by a thermal evaporation step is reported. The epitaxial regrowth repairs most of the morphological defects inherent to meniscus-guided coatings. The resulting film is highly crystalline and features a mobility increased by a factor of three and a relative spread in device characteristics improved by almost half an order of magnitude. This method is easily adaptable to other coating techniques and offers a route toward the fabrication of high-performance, large-area electronics based on highly crystalline thin films of organic semiconductors.
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Affiliation(s)
- Robby Janneck
- IMEC, Kapeldreef 75, Leuven, B-3001, Belgium
- KU Leuven, ESAT, Kasteelpark Arenberg 10, Leuven, B-3001, Belgium
| | - Nicolas Pilet
- Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | | | | | - Paul Heremans
- IMEC, Kapeldreef 75, Leuven, B-3001, Belgium
- KU Leuven, ESAT, Kasteelpark Arenberg 10, Leuven, B-3001, Belgium
| | - Jan Genoe
- IMEC, Kapeldreef 75, Leuven, B-3001, Belgium
- KU Leuven, ESAT, Kasteelpark Arenberg 10, Leuven, B-3001, Belgium
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27
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Mirzayev R, Mustonen K, Monazam MRA, Mittelberger A, Pennycook TJ, Mangler C, Susi T, Kotakoski J, Meyer JC. Buckyball sandwiches. Sci Adv 2017; 3:e1700176. [PMID: 28630925 PMCID: PMC5466370 DOI: 10.1126/sciadv.1700176] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 04/13/2017] [Indexed: 05/30/2023]
Abstract
Two-dimensional (2D) materials have considerably expanded the field of materials science in the past decade. Even more recently, various 2D materials have been assembled into vertical van der Waals heterostacks, and it has been proposed to combine them with other low-dimensional structures to create new materials with hybridized properties. We demonstrate the first direct images of a suspended 0D/2D heterostructure that incorporates C60 molecules between two graphene layers in a buckyball sandwich structure. We find clean and ordered C60 islands with thicknesses down to one molecule, shielded by the graphene layers from the microscope vacuum and partially protected from radiation damage during scanning transmission electron microscopy imaging. The sandwich structure serves as a 2D nanoscale reaction chamber, allowing the analysis of the structure of the molecules and their dynamics at atomic resolution.
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28
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Abstract
The smooth surface of crystalline rubrene films formed through an abrupt heating process provides a valuable platform to study organic homoepitaxy. By varying growth rate and substrate temperature, we are able to manipulate the onset of a transition from layer-by-layer to island growth modes, while the crystalline thin films maintain a remarkably smooth surface (less than 2.3 nm root-mean-square roughness) even with thick (80 nm) adlayers. We also uncover evidence of point and line defect formation in these films, indicating that homoepitaxy under our conditions is not at equilibrium or strain-free. Point defects that are resolved as screw dislocations can be eliminated under closer-to-equilibrium conditions, whereas we are not able to eliminate the formation of line defects within our experimental constraints at adlayer thicknesses above ∼25 nm. We are, however, able to eliminate these line defects by growing on a bulk single crystal of rubrene, indicating that the line defects are a result of strain built into the thin film template. We utilize electron backscatter diffraction, which is a first for organics, to investigate the origin of these line defects and find that they preferentially occur parallel to the (002) plane, which is in agreement with expectations based on calculated surface energies of various rubrene crystal facets. By combining the benefits of crystallinity, low surface roughness, and thickness-tunability, this system provides an important study of attributes valuable to high-performance organic electronic devices.
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Affiliation(s)
- Michael A Fusella
- Department of Electrical Engineering, Princeton University , Princeton, New Jersey 08544 United States
| | - Frank Schreiber
- Institut für Angewandte Physik, Universität Tübingen , Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Kevin Abbasi
- Swagelok Center for Surface Analysis of Materials, Case Western Reserve University , Cleveland, Ohio 44106 United States
| | - Jae Joon Kim
- Polymer Science and Engineering, University of Massachusetts , Amherst, Massachusetts 01003 United States
| | - Alejandro L Briseno
- Polymer Science and Engineering, University of Massachusetts , Amherst, Massachusetts 01003 United States
| | - Barry P Rand
- Department of Electrical Engineering, Princeton University , Princeton, New Jersey 08544 United States
- Andlinger Center for Energy and the Environment, Princeton University , Princeton, New Jersey 08544 United States
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29
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Lorch C, Novák J, Banerjee R, Weimer S, Dieterle J, Frank C, Hinderhofer A, Gerlach A, Carla F, Schreiber F. Influence of C60 co-deposition on the growth kinetics of diindenoperylene–From rapid roughening to layer-by-layer growth in blended organic films. J Chem Phys 2017; 146:052807. [DOI: 10.1063/1.4966583] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Affiliation(s)
- C. Lorch
- Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - J. Novák
- Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
- Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic
- Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Kotlarska 2, CZ-611 37 Brno, Czech Republic
| | - R. Banerjee
- Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
- Department of Physics, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382355, India
| | - S. Weimer
- Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - J. Dieterle
- Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - C. Frank
- Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - A. Hinderhofer
- Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - A. Gerlach
- Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - F. Carla
- ESRF-The European Synchrotron, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - F. Schreiber
- Universität Tübingen, Institut für Angewandte Physik, Auf der Morgenstelle 10, 72076 Tübingen, Germany
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30
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Zykov A, Bommel S, Wolf C, Pithan L, Weber C, Beyer P, Santoro G, Rabe JP, Kowarik S. Diffusion and nucleation in multilayer growth of PTCDI-C8 studied with in situ X-ray growth oscillations and real-time small angle X-ray scattering. J Chem Phys 2017; 146:052803. [DOI: 10.1063/1.4961460] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Affiliation(s)
- Anton Zykov
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin,
Germany
| | - Sebastian Bommel
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin,
Germany
- Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg,
Germany
| | - Christopher Wolf
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin,
Germany
| | - Linus Pithan
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin,
Germany
| | - Christopher Weber
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin,
Germany
| | - Paul Beyer
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin,
Germany
| | - Gonzalo Santoro
- Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg,
Germany
- Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), c/Sor Juana Inés de la Cruz 3, 28049 Madrid,
Spain
| | - Jürgen P. Rabe
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin,
Germany
- IRIS Adlershof, Humboldt-Universität zu Berlin, Zum Großen Windkanal 6, 12489 Berlin,
Germany
| | - Stefan Kowarik
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin,
Germany
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31
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Abstract
Thin-film growth is important for novel functional materials and new generations of devices. The non-equilibrium growth physics involved is very challenging, because the energy landscape for atomic scale processes is determined by many parameters, such as the diffusion and Ehrlich-Schwoebel barriers. We review the in situ real-time techniques of x-ray diffraction (XRD), x-ray growth oscillations and diffuse x-ray scattering (GISAXS) for the determination of structure and morphology on length scales from Å to µm. We give examples of time resolved growth experiments mainly from molecular thin film growth, but also highlight growth of inorganic materials using molecular beam epitaxy (MBE) and electrochemical deposition from liquids. We discuss how scaling parameters of rate equation models and fundamental energy barriers in kinetic Monte Carlo methods can be determined from fits of the real-time x-ray data.
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Affiliation(s)
- Stefan Kowarik
- Institut für Physik, Humboldt Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
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32
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Kleppmann N, Schreiber F, Klapp SHL. Limits of size scalability of diffusion and growth: Atoms versus molecules versus colloids. Phys Rev E 2017; 95:020801. [PMID: 28297845 DOI: 10.1103/physreve.95.020801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Indexed: 06/06/2023]
Abstract
Understanding fundamental growth processes is key to the control of nonequilibrium structure formation for a wide range of materials on all length scales, from atomic to molecular and even colloidal systems. While atomic systems are relatively well studied, molecular and colloidal growth are currently moving more into the focus. This poses the question to what extent growth laws are size scalable between different material systems. We study this question by analyzing the potential energy landscape and performing kinetic Monte Carlo simulations for three representative systems. While submonolayer (island) growth is found to be essentially scalable, we find marked differences when moving into the third (vertical) dimension.
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Affiliation(s)
- N Kleppmann
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - F Schreiber
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - S H L Klapp
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
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33
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Schwartzkopf M, Roth SV. Investigating Polymer-Metal Interfaces by Grazing Incidence Small-Angle X-Ray Scattering from Gradients to Real-Time Studies. Nanomaterials (Basel) 2016; 6:E239. [PMID: 28335367 PMCID: PMC5302712 DOI: 10.3390/nano6120239] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 12/06/2016] [Accepted: 12/07/2016] [Indexed: 01/13/2023]
Abstract
Tailoring the polymer-metal interface is crucial for advanced material design. Vacuum deposition methods for metal layer coating are widely used in industry and research. They allow for installing a variety of nanostructures, often making use of the selective interaction of the metal atoms with the underlying polymer thin film. The polymer thin film may eventually be nanostructured, too, in order to create a hierarchy in length scales. Grazing incidence X-ray scattering is an advanced method to characterize and investigate polymer-metal interfaces. Being non-destructive and yielding statistically relevant results, it allows for deducing the detailed polymer-metal interaction. We review the use of grazing incidence X-ray scattering to elucidate the polymer-metal interface, making use of the modern synchrotron radiation facilities, allowing for very local studies via in situ (so-called "stop-sputter") experiments as well as studies observing the nanostructured metal nanoparticle layer growth in real time.
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Affiliation(s)
| | - Stephan V Roth
- Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, D-22607 Hamburg, Germany.
- KTH Royal Institute of Technology, Department of Fibre and Polymer Technology, Teknikringen 56-58, SE-100 44 Stockholm, Sweden.
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34
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Palczynski K, Herrmann P, Heimel G, Dzubiella J. Characterization of step-edge barrier crossing of para-sexiphenyl on the ZnO (101[combining macron]0) surface. Phys Chem Chem Phys 2016; 18:25329-25341. [PMID: 27711631 DOI: 10.1039/c6cp05251g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mass transport processes of conjugated organic molecules (COMs) on inorganic surfaces are essential elements in thin film deposition for hybrid optoelectronic devices. Defects and in particular surface step-edges dictate the molecular nucleation and growth morphology, which itself determine many physical properties of the resulting hybrid interface. Here, we explore the detailed molecular kinetics and transport rates of a single physisorbed para-sexiphenyl (p-6P) molecule crossing a step-edge (a "hetero-Ehrlich-Schwoebel barrier") on the inorganic ZnO (101[combining macron]0) surface by a combination of all-atom molecular dynamics simulations and passage time theory. We determine temperature- and charge-dependent (free) energy landscapes, position-dependent diffusion coefficients, and ultimately the mean first passage time over the step-edges. We find two completely different step-edge crossing mechanisms, the occurrence and rates of which simultaneously depend on both electrostatic and thermal molecule-surface coupling. In weakly coupled systems, the molecule crosses the step relatively quickly (in nanoseconds) by log-roll mechanisms while for strongly coupled systems, it crosses relatively slowly (in microseconds) in a strictly perpendicular fashion. In the latter process, "internal friction" from intramolecular bending and torsional degrees of freedom contribute a significant corrugation to the overall crossing barrier. Furthermore, we show that crossing pathways can also change qualitatively with step-edge height. The great complexity in hetero-barrier crossing of COMs (in contrast to simple atoms) revealed in this study has implications on the interpretation and possible control of nucleation and growth mechanisms at surface defects in hybrid systems.
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Affiliation(s)
- Karol Palczynski
- Institut für Weiche Materie und Funktionale Materialien, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, 14109 Berlin, Germany. and Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Philipp Herrmann
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Georg Heimel
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Joachim Dzubiella
- Institut für Weiche Materie und Funktionale Materialien, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, 14109 Berlin, Germany. and Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
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35
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Lorch C, Broch K, Belova V, Duva G, Hinderhofer A, Gerlach A, Jankowski M, Schreiber F. Growth and annealing kinetics of α-sexithiophene and fullerene C60mixed films. J Appl Crystallogr 2016. [DOI: 10.1107/s1600576716009936] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Thin films of α-sexithiophene (6T) and C60mixtures deposited on nSiO substrates at 303 and 373 K were investigated in real time andin situduring the film growth using X-ray diffraction. The mixtures are observed to contain the well known 6T low-temperature crystal phase and the β phase, which usually coexist in pure 6T films. The addition of C60modifies the structure to almost purely β-phase-dominated films if the substrate is at 303 K. In contrast, at 373 K the low-temperature crystal phase of 6T dominates the film growth of the mixtures. Post-growth annealing experiments up to 373 K on equimolar mixtures and pure 6T films were also performed and followed in real time with X-ray diffraction. Annealing of pure 6T films results in a strong increase of film ordering, whereas annealing of equimolar 6T:C60mixed films does not induce any significant changes in the film structure. These results lend further support to theories about the important influence of C60on the growth behaviour and structure formation process of 6T in mixtures of the two materials.
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36
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Freund S, Hinaut A, Pawlak R, Liu SX, Decurtins S, Meyer E, Glatzel T. Morphology Change of C60 Islands on Organic Crystals Observed by Atomic Force Microscopy. ACS Nano 2016; 10:5782-5788. [PMID: 27219352 DOI: 10.1021/acsnano.5b07971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Organic-organic heterojunctions are nowadays highly regarded materials for light-emitting diodes, field-effect transistors, and photovoltaic cells with the prospect of designing low-cost, flexible, and efficient electronic devices.1-3 However, the key parameter of optimized heterojunctions relies on the choice of the molecular compounds as well as on the morphology of the organic-organic interface,4 which thus requires fundamental studies. In this work, we investigated the deposition of C60 molecules at room temperature on an organic layer compound, the salt bis(benzylammonium)bis(oxalato)cupurate(II), by means of noncontact atomic force microscopy. Three-dimensional molecular islands of C60 having either triangular or hexagonal shapes are formed on the substrate following a "Volmer-Weber" type of growth. We demonstrate the dynamical reshaping of those C60 nanostructures under the local action of the AFM tip at room temperature. The dissipated energy is about 75 meV and can be interpreted as the activation energy required for this migration process.
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Affiliation(s)
- Sara Freund
- Department of Physics, University of Basel , Klingelbergstraße 82, 4056 Basel, Switzerland
| | - Antoine Hinaut
- Department of Physics, University of Basel , Klingelbergstraße 82, 4056 Basel, Switzerland
| | - Rémy Pawlak
- Department of Physics, University of Basel , Klingelbergstraße 82, 4056 Basel, Switzerland
| | - Shi-Xia Liu
- Department of Chemistry and Biochemistry, University of Bern , Freiestraße 3, 3012 Bern, Switzerland
| | - Silvio Decurtins
- Department of Chemistry and Biochemistry, University of Bern , Freiestraße 3, 3012 Bern, Switzerland
| | - Ernst Meyer
- Department of Physics, University of Basel , Klingelbergstraße 82, 4056 Basel, Switzerland
| | - Thilo Glatzel
- Department of Physics, University of Basel , Klingelbergstraße 82, 4056 Basel, Switzerland
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37
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Acevedo YM, Cantrell RA, Berard PG, Koch DL, Clancy P. Multiscale Simulation and Modeling of Multilayer Heteroepitactic Growth of C60 on Pentacene. Langmuir 2016; 32:3045-3056. [PMID: 26937559 DOI: 10.1021/acs.langmuir.5b04500] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We apply multiscale methods to describe the strained growth of multiple layers of C60 on a thin film of pentacene. We study this growth in the presence of a monolayer pentacene step to compare our simulations to recent experimental studies by Breuer and Witte of submonolayer growth in the presence of monolayer steps. The molecular-level details of this organic semiconductor interface have ramifications on the macroscale structural and electronic behavior of this system and allow us to describe several unexplained experimental observations for this system. The growth of a C60 thin film on a pentacene surface is complicated by the differing crystal habits of the two component species, leading to heteroepitactical growth. In order to probe this growth, we use three computational methods that offer different approaches to coarse-graining the system and differing degrees of computational efficiency. We present a new, efficient reaction-diffusion continuum model for 2D systems whose results compare well with mesoscale kinetic Monte Carlo (KMC) results for submonolayer growth. KMC extends our ability to simulate multiple layers but requires a library of predefined rates for event transitions. Coarse-grained molecular dynamics (CGMD) circumvents KMC's need for predefined lattices, allowing defects and grain boundaries to provide a more realistic thin film morphology. For multilayer growth, in this particularly suitable candidate for coarse-graining, CGMD is a preferable approach to KMC. Combining the results from these three methods, we show that the lattice strain induced by heteroepitactical growth promotes 3D growth and the creation of defects in the first monolayer. The CGMD results are consistent with experimental results on the same system by Conrad et al. and by Breuer and Witte in which C60 aggregates change from a 2D structure at low temperature to 3D clusters along the pentacene step edges at higher temperatures.
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Affiliation(s)
- Yaset M Acevedo
- School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Rebecca A Cantrell
- School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Philip G Berard
- School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Donald L Koch
- School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States
| | - Paulette Clancy
- School of Chemical and Biomolecular Engineering, Cornell University , Ithaca, New York 14853, United States
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38
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Bein B, Hsing HC, Callori SJ, Sinsheimer J, Chinta PV, Headrick RL, Dawber M. In situ X-ray diffraction and the evolution of polarization during the growth of ferroelectric superlattices. Nat Commun 2015; 6:10136. [PMID: 26634894 PMCID: PMC4686826 DOI: 10.1038/ncomms10136] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 11/06/2015] [Indexed: 11/25/2022] Open
Abstract
In epitaxially strained ferroelectric thin films and superlattices, the ferroelectric transition temperature can lie above the growth temperature. Ferroelectric polarization and domains should then evolve during the growth of a sample, and electrostatic boundary conditions may play an important role. In this work, ferroelectric domains, surface termination, average lattice parameter and bilayer thickness are simultaneously monitored using in situ synchrotron X-ray diffraction during the growth of BaTiO3/SrTiO3 superlattices on SrTiO3 substrates by off-axis radio frequency magnetron sputtering. The technique used allows for scan times substantially faster than the growth of a single layer of material. Effects of electric boundary conditions are investigated by growing the same superlattice alternatively on SrTiO3 substrates and 20 nm SrRuO3 thin films on SrTiO3 substrates. These experiments provide important insights into the formation and evolution of ferroelectric domains when the sample is ferroelectric during the growth process.
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Affiliation(s)
- Benjamin Bein
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
| | - Hsiang-Chun Hsing
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
| | - Sara J. Callori
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
| | - John Sinsheimer
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
| | - Priya V. Chinta
- Department of Physics, Cook Physical Science Building, University of Vermont, Burlington, Vermont 05405, USA
| | - Randall L. Headrick
- Department of Physics, Cook Physical Science Building, University of Vermont, Burlington, Vermont 05405, USA
| | - Matthew Dawber
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
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39
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Schwartzkopf M, Santoro G, Brett CJ, Rothkirch A, Polonskyi O, Hinz A, Metwalli E, Yao Y, Strunskus T, Faupel F, Müller-Buschbaum P, Roth SV. Real-Time Monitoring of Morphology and Optical Properties during Sputter Deposition for Tailoring Metal-Polymer Interfaces. ACS Appl Mater Interfaces 2015; 7:13547-56. [PMID: 26030314 DOI: 10.1021/acsami.5b02901] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The reproducible low-cost fabrication of functional metal-polymer nanocomposites with tailored optoelectronic properties for advanced applications remains a major challenge in applied nanotechnology. To obtain full control over the nanostructural evolution at the metal-polymer interface and its impact on optoelectronic properties, we employed combined in situ time-resolved microfocus grazing incidence small angle X-ray scattering (μGISAXS) with in situ UV/vis specular reflectance spectroscopy (SRS) during sputter deposition of gold on thin polystyrene films. On the basis of the temporal evolution of the key scattering features in the real-time μGISAXS experiment, we directly observed four different growth regimes: nucleation, isolated island growth, growth of larger aggregates via partial coalescence, and continuous layer growth. Moreover, their individual thresholds were identified with subnanometer resolution and correlated to the changes in optical properties. During sputter deposition, a change in optical reflectivity of the pristine gray-blue PS film was observed ranging from dark blue color due to the presence of isolated nanoclusters at the interface to bright red color from larger Au aggregates. We used simplified geometrical assumptions to model the evolution of average real space parameters (distance, size, density, contact angle) in excellent agreement with the qualitative observation of key scattering features. A decrease of contact angles was observed during the island-to-percolation transition and confirmed by simulations. Furthermore, a surface diffusion coefficient according to the kinetic freezing model and interfacial energy of Au on PS at room temperature were calculated based on a real-time experiment. The morphological characterization is complemented by X-ray reflectivity, optical, and electron microscopy. Our study permits a better understanding of the growth kinetics of gold clusters and their self-organization into complex nanostructures on polymer substrates. It opens up the opportunity to improve nanofabrication and tailoring of metal-polymer nanostructures for optoelectronic applications, organic photovoltaics, and plasmonic-enhanced technologies.
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Affiliation(s)
- Matthias Schwartzkopf
- †Photon Science, Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, D-22607 Hamburg, Germany
| | - Gonzalo Santoro
- †Photon Science, Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, D-22607 Hamburg, Germany
| | - Calvin J Brett
- †Photon Science, Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, D-22607 Hamburg, Germany
| | - André Rothkirch
- †Photon Science, Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, D-22607 Hamburg, Germany
| | - Oleksandr Polonskyi
- ‡Lehrstuhl für Materialverbunde, Institut für Materialwissenschaft, Christian Albrechts-Universität zu Kiel, Kaiserstr.2, D-24143 Kiel, Germany
| | - Alexander Hinz
- ‡Lehrstuhl für Materialverbunde, Institut für Materialwissenschaft, Christian Albrechts-Universität zu Kiel, Kaiserstr.2, D-24143 Kiel, Germany
| | - Ezzeldin Metwalli
- §Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Str. 1, D-85748 Garching, Germany
| | - Yuan Yao
- §Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Str. 1, D-85748 Garching, Germany
| | - Thomas Strunskus
- ‡Lehrstuhl für Materialverbunde, Institut für Materialwissenschaft, Christian Albrechts-Universität zu Kiel, Kaiserstr.2, D-24143 Kiel, Germany
| | - Franz Faupel
- ‡Lehrstuhl für Materialverbunde, Institut für Materialwissenschaft, Christian Albrechts-Universität zu Kiel, Kaiserstr.2, D-24143 Kiel, Germany
| | - Peter Müller-Buschbaum
- §Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, James-Franck-Str. 1, D-85748 Garching, Germany
| | - Stephan V Roth
- †Photon Science, Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, D-22607 Hamburg, Germany
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Walter P, Dippel AC, Pflaum K, Wernecke J, van den Hurk J, Blume J, Klemradt U. A compact and low-weight sputtering unit for in situ investigations of thin film growth at synchrotron radiation beamlines. Rev Sci Instrum 2015; 86:053906. [PMID: 26026535 DOI: 10.1063/1.4918620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this work, we report on a highly variable, compact, and light high-vacuum sputter deposition unit designed for in situ experiments using synchrotron radiation facilities. The chamber can be mounted at various synchrotron beamlines for scattering experiments in grazing incidence geometry. The sample position and the large exit window allow to perform x-ray experiments up to large q values. The sputtering unit is easy to mount on existing experimental setups and can be remote-controlled. In this paper, we describe in detail the design and the performance of the new sputtering chamber and present the installation of the apparatus at different 3rd generation light sources. Furthermore, we describe the different measurement options and present some selected results. The unit has been successfully commissioned and is now available for users at PETRA III at DESY.
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Affiliation(s)
- P Walter
- Deutsches Elektronen-Synchrotron, Notkestr. 85, D-22607 Hamburg, Germany
| | - A-C Dippel
- Deutsches Elektronen-Synchrotron, Notkestr. 85, D-22607 Hamburg, Germany
| | - K Pflaum
- Deutsches Elektronen-Synchrotron, Notkestr. 85, D-22607 Hamburg, Germany
| | - J Wernecke
- Deutsches Elektronen-Synchrotron, Notkestr. 85, D-22607 Hamburg, Germany
| | - J van den Hurk
- Institut für Werkstoffe der Elektrotechnik II (IWE II) and JARA-FIT, RWTH Aachen University, Sommerfeldstr. 24, D-52074 Aachen, Germany
| | - J Blume
- Deutsches Elektronen-Synchrotron, Notkestr. 85, D-22607 Hamburg, Germany
| | - U Klemradt
- 2nd. Institute of Physics B and JARA-FIT, RWTH Aachen University, Otto-Blumenthal-Str. 1, D-52074 Aachen, Germany
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