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Bordovalos A, Subedi B, Chen L, Song Z, Yan Y, Podraza NJ. Implications of Electron Transport Layer and Back Metal Contact Variations in Tin-Lead Perovskite Solar Cells Assessed by Spectroscopic Ellipsometry and External Quantum Efficiency. ACS APPLIED MATERIALS & INTERFACES 2023; 15:19730-19740. [PMID: 37022937 DOI: 10.1021/acsami.3c01849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The structural and optical properties of hybrid organic-inorganic metal halide perovskite solar cells are measured by spectroscopic ellipsometry to reveal an optically distinct interfacial layer among the back contact metal, charge transport, and absorber layers. Understanding how this interfacial layer impacts performance is essential for developing higher performing solar cells. This interfacial layer is modeled by Bruggeman effective medium approximations (EMAs) to contain perovskite, C60, BCP, and metal. External quantum efficiency (EQE) simulations that consider scattering, electronic losses, and the formation of nonparallel interfaces are created with input derived from ellipsometry structural-optical models and compared with experimental EQE to estimate optical losses. This nonplanar interface causes optical losses in short circuit current density (JSC) of up to 1.2 mA cm-2. A study of glass/C60/SnO2/Ag or Cu and glass/C60/BCP/Ag film stacks shows that C60 and BCP mix, but replacing BCP with SnO2 can prevent mixing between the ETLs to prevent contact between C60 and back contact metal and enable the formation of a planar interface between ETLs and back contact metals.
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Affiliation(s)
- Alexander Bordovalos
- Department of Physics and Astronomy & Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, United States
| | - Biwas Subedi
- Department of Physics and Astronomy & Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, United States
| | - Lei Chen
- Department of Physics and Astronomy & Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, United States
| | - Zhaoning Song
- Department of Physics and Astronomy & Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, United States
| | - Yanfa Yan
- Department of Physics and Astronomy & Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, United States
| | - Nikolas J Podraza
- Department of Physics and Astronomy & Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, United States
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Wang J, Peng L, Zhai F, Tang D, Gao F, Zhang X, Chen R, Zhou L, Jiang XJ. Polarized angle-resolved spectral reflectometry for real-time ultra-thin film measurement. OPTICS EXPRESS 2023; 31:6552-6565. [PMID: 36823908 DOI: 10.1364/oe.481389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 01/27/2023] [Indexed: 06/18/2023]
Abstract
We propose a polarized, angle-resolved spectral (PARS) reflectometry for simultaneous thickness and refractive-index measurement of ultra-thin films in real time. This technology acquires a two-dimensional, angle-resolved spectrum through a dual-angle analyzer in a single shot by radially filtering the back-focal-plane image of a high-NA objective for dispersion analysis. Thus, film parameters, including thickness and refractive indices, are precisely fitted from the hyper-spectrum in angular and wavelength domains. Through a high-accuracy spectral calibration, a primary PARS system was built. Its accuracy was carefully verified by testing a set of SiO2 thin films of thicknesses within two µm grown on monocrystalline-Si substrates against a commercial spectroscopic ellipsometer. Results show that the single-shot PARS reflectometry results in a root-mean-square absolute accuracy error of ∼1 nm in film thickness measurement without knowing its refractive indices.
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3
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Kenaz R, Rapaport R. Mapping spectroscopic micro-ellipsometry with sub-5 microns lateral resolution and simultaneous broadband acquisition at multiple angles. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:023908. [PMID: 36859011 DOI: 10.1063/5.0123249] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 01/29/2023] [Indexed: 06/18/2023]
Abstract
Spectroscopic ellipsometry is a widely used optical technique in both industry and research for determining the optical properties and thickness of thin films. The effective use of spectroscopic ellipsometry on micro-structures is inhibited by technical limitations on the lateral resolution and data acquisition rate. Here, we introduce a spectroscopic micro-ellipsometer (SME), capable of recording spectrally resolved ellipsometric data simultaneously at multiple angles of incidence in a single measurement of a few seconds, with a lateral resolution down to 2 μm in the visible spectral range. The SME can be easily integrated into generic optical microscopes by the addition of a few standard optical components. We demonstrate complex refractive index and thickness measurements by using the SME, which are in excellent agreement with a commercial spectroscopic ellipsometer. The high lateral resolution is displayed by complex refractive index and thickness maps over micron-scale areas. As an application for its accuracy and high lateral resolution, the SME can characterize the optical properties and number of layers of exfoliated transition-metal dichalcogenides and graphene, for structures that are a few microns in size.
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Affiliation(s)
- Ralfy Kenaz
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Ronen Rapaport
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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Chang LM, Feng TM, Lin KW, Tseng HY, Li CC, Guo DY, Jau HC, Wang CT, Lin TH. Electrotunable 180° achromatic linear polarization rotator based on a dual-frequency liquid crystal. OPTICS EXPRESS 2022; 30:4886-4894. [PMID: 35209461 DOI: 10.1364/oe.447256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 01/24/2022] [Indexed: 06/14/2023]
Abstract
Linear polarization rotators have been widely used in optical systems. Commonly used polarization rotators are still beset by strong dispersion and thus restricted spectral bandwidth of operation. This leads to the development of achromatic or broadband alternatives, but most of them incorporate multiple waveplates for retardation compensation, which comes at the cost of increased complexity and reduced flexibility in operation and system design. Here, we demonstrate a single-element achromatic polarization rotator based on a thin film of dual-frequency chiral liquid crystal. The angle of polarization rotation is electrically tunable from 0° to 180° with low dispersion (±3°) in the entire visible spectrum, and a high degree of linear polarization (>95%) at the output.
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Cho YJ, Chegal W. Measurement uncertainty evaluation procedures and applications for various types of multichannel rotating-element spectroscopic ellipsometers. OPTICS EXPRESS 2021; 29:39428-39448. [PMID: 34809308 DOI: 10.1364/oe.443311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/21/2021] [Indexed: 06/13/2023]
Abstract
A universal measurement uncertainty evaluation procedure is required for different types of multichannel rotating-element spectroscopic ellipsometers (RE-SEs) used in modern semiconductor industry. Herein, an improved uncertainty evaluation procedure, based on the universal measurement model functions and implicit function theorem, is introduced for unknown optical parameters of a sample. In addition, we develop a measurement standard instrument that can solve the error problems related to the basic principles of the multichannel RE-SEs used in the industrial field and present an example of applying the proposed uncertainty evaluation method to this standard instrument. Accordingly, the measurement performance for several types of real-time RE-SEs can be quantitatively compared. It can also be used for standardization, instrumentation, and measurement optimization.
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Alanazi N, Alodhayb AN, Almutairi A, Alshehri H, AlYemni S, Alsowygh G, Abdulmawla S, Shamma K, Albrithen H, Muthuramamoorthy M, Almuqrin AH. Quartz Tuning Fork Sensor-Based Dosimetry for Sensitive Detection of Gamma Radiation. MATERIALS (BASEL, SWITZERLAND) 2021; 14:7035. [PMID: 34832435 PMCID: PMC8619227 DOI: 10.3390/ma14227035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 11/03/2021] [Accepted: 11/15/2021] [Indexed: 01/18/2023]
Abstract
This study generally relates to nuclear sensors and specifically to detecting nuclear and electromagnetic radiation using an ultrasensitive quartz tuning fork (QTF) sensor. We aim to detect low doses of gamma radiation with fast response time using QTF. Three different types of QTFs (uncoated and gold coated) were used in this study in order to investigate their sensitivity to gamma radiations. Our results show that a thick gold coating on QTF can enhance the quality factor and increase the resonance frequency from 32.7 to 32.9 kHz as compared to uncoated QTF. The results also show that increasing the surface area of the gold coating on the QTF can significantly enhance the sensitivity of the QTF to radiation. We investigated the properties of gold-coated and uncoated QTFs before and after irradiation by scanning electron microscopy. We further investigated the optical properties of SiO2 wafers (quartz) by spectroscopic ellipsometry (SE). The SE studies revealed that even a small change in the microstructure of the material caused by gamma radiation would have an impact on mechanical properties of QTF, resulting in a shift in resonance frequency. Overall, the results of the experiments demonstrated the feasibility of using QTF sensors as an easy to use, low-cost, and sensitive radiation detector.
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Affiliation(s)
- Nadyah Alanazi
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (N.A.); (A.N.A.); (A.A.); (H.A.); (S.A.); (G.A.); (S.A.); (K.S.); (H.A.)
| | - Abdullah N. Alodhayb
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (N.A.); (A.N.A.); (A.A.); (H.A.); (S.A.); (G.A.); (S.A.); (K.S.); (H.A.)
- Research Chair for Tribology, Surface, and Interface Sciences, Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
- King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451, Saudi Arabia;
| | - Atheer Almutairi
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (N.A.); (A.N.A.); (A.A.); (H.A.); (S.A.); (G.A.); (S.A.); (K.S.); (H.A.)
| | - Hanan Alshehri
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (N.A.); (A.N.A.); (A.A.); (H.A.); (S.A.); (G.A.); (S.A.); (K.S.); (H.A.)
| | - Sarah AlYemni
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (N.A.); (A.N.A.); (A.A.); (H.A.); (S.A.); (G.A.); (S.A.); (K.S.); (H.A.)
| | - Ghadah Alsowygh
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (N.A.); (A.N.A.); (A.A.); (H.A.); (S.A.); (G.A.); (S.A.); (K.S.); (H.A.)
| | - Sabaa Abdulmawla
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (N.A.); (A.N.A.); (A.A.); (H.A.); (S.A.); (G.A.); (S.A.); (K.S.); (H.A.)
| | - Khaled Shamma
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (N.A.); (A.N.A.); (A.A.); (H.A.); (S.A.); (G.A.); (S.A.); (K.S.); (H.A.)
- King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451, Saudi Arabia;
| | - Hamad Albrithen
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (N.A.); (A.N.A.); (A.A.); (H.A.); (S.A.); (G.A.); (S.A.); (K.S.); (H.A.)
- Research Chair for Tribology, Surface, and Interface Sciences, Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
- King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451, Saudi Arabia;
- K.A.CARE Energy Research and Innovation Center at Riyadh, Riyadh 11451, Saudi Arabia
| | | | - Aljawhara H. Almuqrin
- Department of Physics, College of Science, Princess Nourah bint Abdulrahman University, Riyadh 11564, Saudi Arabia
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Impact of Humidity and Temperature on the Stability of the Optical Properties and Structure of MAPbI 3, MA 0.7FA 0.3PbI 3 and (FAPbI 3) 0.95(MAPbBr 3) 0.05 Perovskite Thin Films. MATERIALS 2021; 14:ma14144054. [PMID: 34300973 PMCID: PMC8307273 DOI: 10.3390/ma14144054] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/23/2021] [Accepted: 06/30/2021] [Indexed: 11/17/2022]
Abstract
In situ real-time spectroscopic ellipsometry (RTSE) measurements have been conducted on MAPbI3, MA0.7FA0.3PbI3, and (FAPbI3)0.95(MAPbBr3)0.05 perovskite thin films when exposed to different levels of relative humidity at given temperatures over time. Analysis of RTSE measurements track changes in the complex dielectric function spectra and structure, which indicate variations in stability influenced by the underlying material, preparation method, and perovskite composition. MAPbI3 and MA0.7FA0.3PbI3 films deposited on commercial fluorine-doped tin oxide coated glass are more stable than corresponding films deposited on soda lime glass directly. (FAPbI3)0.95(MAPbBr3)0.05 films on soda lime glass showed improved stability over the other compositions regardless of the substrate, and this is attributed to the preparation method as well as the final composition.
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Vala D, Koleják P, Postava K, Kildemo M, Provazníková P, Pištora J. Effects of optical activity to Mueller matrix ellipsometry of composed waveplates. OPTICS EXPRESS 2021; 29:10434-10450. [PMID: 33820178 DOI: 10.1364/oe.418186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 02/23/2021] [Indexed: 06/12/2023]
Abstract
Mueller matrix ellipsometry has been used to precisely characterize quartz waveplates for demanding applications in the semiconductor industry and high precision polarimetry. We have found this experimental technique to be beneficial to use because it enables us to obtain absolute and precise measurement of retardation in a wide spectral range, waveplate orientation, and compound waveplate adjustment. In this paper, the necessity of including the optical activity in the Mueller matrix model and data treatment is demonstrated. Particularly, the optical activity of the quartz influences the adjustment of misalignment between the perpendicularly oriented waveplates of the compound biplate. We demonstrate that omitting the optical activity from the model leads to inaccurate values of the misalignment. In addition, the depolarization effects caused by a finite monochromator bandwidth is included in the model. Incorporation of the optical activity to the Mueller matrix model has required a development of rigorous theory based on appropriate constitutive equations. The generalized Yeh's matrix algebra to bianisotropic media has been used for the calculation of the eigenmodes propagation in chiral materials with reduced symmetry. Based on the applied method, the authors have proposed approximated analytical form of the Mueller matrix representing optically active waveplate and biplate and provided discussion on the analytical and numerical limits of the method.
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9
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Zaman Q, S Costa J, R J Barreto A, F D F Araujo J, D Carlos L, N Carneiro Neto A, Cremona M, Ahmed Z, S Cruz AF, P Souza NW, Q da Costa K, Dmitriev V, Laurenzana A, Margheri F, Del Rosso T. Dielectric-Loaded Waveguides as Advanced Platforms for Diagnostics and Application of Transparent Thin Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:3248-3260. [PMID: 33683133 DOI: 10.1021/acs.langmuir.0c02862] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
An alternative approach to classical surface plasmon resonance spectroscopy is dielectric-loaded waveguide (DLWG) spectroscopy, widely used in the past decades to investigate bio-interaction kinetics. Despite their wide application, a successful and clear approach to use the DLWGs for the one-step simultaneous determination of both the thickness and refractive index of organic thin films is absent in the literature. We propose here, for the first time, an experimental protocol based on the multimodal nature of DLWGs to be followed in order to evaluate the optical constants and thickness of transparent thin films with a unique measurement. The proposed method is general and can be applied to every class of transparent organic materials, with a resolution and accuracy which depend on the nature of the external medium (gaseous or liquid), the geometrical characteristics of the DLWG, and the values of both the thickness and dielectric constant of the thin film. From the experimental point of view, the method is demonstrated in a nitrogen environment with an accuracy of about 3%, for the special case of electroluminescent thin films of Eu3+β-diketonate complexes, with an average thickness of about 20 nm. The high value of the refractive index measured for the thin film with the Eu(btfa)3(t-bpete) complex was confirmed by the use of a spectroscopic model based on the Judd-Ofelt theory, in which the magnetic dipole transition 5D0 → 7F1 (Eu3+) for similar films containing Eu3+ complexes is taken as a reference. The DLWGs are finally applied to control the refractive index changes of the organic thin films under UVA irradiation, with potential applications in dosimetry and monitoring light-induced transformation in organic thin films.
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Affiliation(s)
- Quaid Zaman
- Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, Rua Marques de São Vicente, 22451-900 Rio de Janeiro, Brazil
| | - Jefferson S Costa
- Department of Electrical Engineering, Federal University of Pará, Belém, 66075-110 Pará, Brazil
| | - Arthur R J Barreto
- Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, Rua Marques de São Vicente, 22451-900 Rio de Janeiro, Brazil
| | - Jefferson F D F Araujo
- Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, Rua Marques de São Vicente, 22451-900 Rio de Janeiro, Brazil
| | - Luís D Carlos
- Phantom-g, CICECO-Aveiro Institute of Materials, Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Albano N Carneiro Neto
- Phantom-g, CICECO-Aveiro Institute of Materials, Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Marco Cremona
- Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, Rua Marques de São Vicente, 22451-900 Rio de Janeiro, Brazil
| | - Zubair Ahmed
- Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, Rua Marques de São Vicente, 22451-900 Rio de Janeiro, Brazil
| | - André Felipe S Cruz
- Department of Electrical Engineering, Federal University of Pará, Belém, 66075-110 Pará, Brazil
| | - Nadson Welkson P Souza
- Department of Electrical Engineering, Federal University of Pará, Belém, 66075-110 Pará, Brazil
| | - Karlo Q da Costa
- Department of Electrical Engineering, Federal University of Pará, Belém, 66075-110 Pará, Brazil
| | - Victor Dmitriev
- Department of Electrical Engineering, Federal University of Pará, Belém, 66075-110 Pará, Brazil
| | - Anna Laurenzana
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Viale G.B. Morgagni 50, 50134 Florence, Italy
| | - Francesca Margheri
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Viale G.B. Morgagni 50, 50134 Florence, Italy
| | - Tommaso Del Rosso
- Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, Rua Marques de São Vicente, 22451-900 Rio de Janeiro, Brazil
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Subedi B, Song Z, Chen C, Li C, Ghimire K, Junda MM, Subedi I, Yan Y, Podraza NJ. Optical and Electronic Losses Arising from Physically Mixed Interfacial Layers in Perovskite Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2021; 13:4923-4934. [PMID: 33470116 DOI: 10.1021/acsami.0c16364] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Perovskite solar cell device performance is affected by optical and electronic losses. To minimize these losses in solar cells, it is important to identify their sources. Here, we report the optical and electronic losses arising from physically mixed interfacial layers between the adjacent component materials in highly efficient two terminal (2T) all-perovskite tandem, single-junction wide-bandgap, and single-junction narrow-bandgap perovskite-based solar cells. Physically mixed interfacial layers as the sources of optical and electronic losses are identified from spectroscopic ellipsometry measurements and data analysis followed by comparisons of simulated and measured external quantum efficiency spectra. Parasitic absorbance in the physically mixed regions between silver metal electrical contacts and electron transport layers (ETLs) near the back contact and a physical mixture of commercial indium tin oxide and hole transport layers (HTL) near the front electrical contact lead to substantial optical loss. A lower-density void + perovskite nucleation layer formed during perovskite deposition at the interface between the perovskite absorber layer and the HTL causes electronic losses because of incomplete collection of photogenerated carriers likely originating from poor coverage and passivation of the initially nucleating grains.
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Affiliation(s)
- Biwas Subedi
- Department of Physics and Astronomy and the Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo 43606, Ohio, United States
| | - Zhaoning Song
- Department of Physics and Astronomy and the Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo 43606, Ohio, United States
| | - Cong Chen
- Department of Physics and Astronomy and the Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo 43606, Ohio, United States
| | - Chongwen Li
- Department of Physics and Astronomy and the Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo 43606, Ohio, United States
| | - Kiran Ghimire
- Department of Physics and Astronomy and the Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo 43606, Ohio, United States
| | - Maxwell M Junda
- Department of Physics and Astronomy and the Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo 43606, Ohio, United States
| | - Indra Subedi
- Department of Physics and Astronomy and the Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo 43606, Ohio, United States
| | - Yanfa Yan
- Department of Physics and Astronomy and the Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo 43606, Ohio, United States
| | - Nikolas J Podraza
- Department of Physics and Astronomy and the Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo 43606, Ohio, United States
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Subedi B, Li C, Junda MM, Song Z, Yan Y, Podraza NJ. Effects of intrinsic and atmospherically induced defects in narrow bandgap (FASnI 3) x(MAPbI 3) 1-x perovskite films and solar cells. J Chem Phys 2020; 152:064705. [PMID: 32061228 DOI: 10.1063/1.5126867] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Narrow bandgap mixed tin (Sn) + lead (Pb) perovskites are necessary for the bottom sub-cell absorber in high efficiency all-perovskite polycrystalline tandem solar cells. We report on the impact of mixed cation composition and atmospheric exposure of perovskite films on sub-gap absorption in films and performance of solar cells based on narrow bandgap mixed formamidinium (FA) + methylammonium (MA) and Sn + Pb halide perovskites, (FASnI3)x(MAPbI3)1-x. Structural and optical properties of 0.3 ≤ x ≤ 0.8 (FASnI3)x(MAPbI3)1-x perovskite thin film absorbers with bandgaps ranging from 1.25 eV (x = 0.6) to 1.34 eV (x = 0.3) are probed with and without atmospheric exposure. Urbach energy, which quantifies the amount of sub-gap absorption, is tracked for pristine perovskite films as a function of composition, with x = 0.6 and 0.3 demonstrating the lowest and highest Urbach energies of 23 meV and 36 meV, respectively. Films with x = 0.5 and 0.6 compositions show less degradation upon atmospheric exposure than higher or lower Sn-content films having greater sub-gap absorption. The corresponding solar cells based on the x = 0.6 absorber show the highest device performance. Despite having a low Urbach energy, higher Sn-content solar cells show reduced device performances as the amount of degradation via oxidation is the most substantial.
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Affiliation(s)
- Biwas Subedi
- Department of Physics and Astronomy and The Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, USA
| | - Chongwen Li
- Department of Physics and Astronomy and The Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, USA
| | - Maxwell M Junda
- Department of Physics and Astronomy and The Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, USA
| | - Zhaoning Song
- Department of Physics and Astronomy and The Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, USA
| | - Yanfa Yan
- Department of Physics and Astronomy and The Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, USA
| | - Nikolas J Podraza
- Department of Physics and Astronomy and The Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606, USA
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Uprety P, Subedi I, Junda MM, Collins RW, Podraza NJ. Photogenerated Carrier Transport Properties in Silicon Photovoltaics. Sci Rep 2019; 9:19015. [PMID: 31831793 PMCID: PMC6908689 DOI: 10.1038/s41598-019-55173-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 11/22/2019] [Indexed: 11/29/2022] Open
Abstract
Electrical transport parameters for active layers in silicon (Si) wafer solar cells are determined from free carrier optical absorption using non-contacting optical Hall effect measurements. Majority carrier transport parameters [carrier concentration (N), mobility (μ), and conductivity effective mass (m*)] are determined for both the n-type emitter and p-type bulk wafer Si of an industrially produced aluminum back surface field (Al-BSF) photovoltaic device. From measurements under 0 and ±1.48 T external magnetic fields and nominally “dark” conditions, the following respective [n, p]-type Si parameters are obtained: N = [(3.6 ± 0.1) × 1018 cm−3, (7.6 ± 0.1) × 1015 cm−3]; μ = [166 ± 6 cm2/Vs, 532 ± 12 cm2/Vs]; and m* = [(0.28 ± 0.03) × me, (0.36 ± 0.02) × me]. All values are within expectations for this device design. Contributions from photogenerated carriers in both regions of the p-n junction are obtained from measurements of the solar cell under “light” 1 sun illumination (AM1.5 solar irradiance spectrum). From analysis of combined dark and light optical Hall effect measurements, photogenerated minority carrier transport parameters [minority carrier concentration (Δp or Δn) and minority carrier mobility (μh or μe)] under 1 sun illumination for both n- and p-type Si components of the solar cell are determined. Photogenerated minority carrier concentrations are [(7.8 ± 0.2) × 1016 cm−3, (2.2 ± 0.2) × 1014 cm−3], and minority carrier mobilities are [331 ± 191 cm2/Vs, 766 ± 331 cm2/Vs], for the [n, p]-type Si, respectively, values that are within expectations from literature. Using the dark majority carrier concentration and the effective equilibrium minority carrier concentration under 1 sun illumination, minority carrier effective lifetime and diffusion length are calculated in the n-type emitter and p-type wafer Si with the results also being consistent with literature. Solar cell device performance parameters including photovoltaic device efficiency, open circuit voltage, fill factor, and short circuit current density are also calculated from these transport parameters obtained via optical Hall effect using the diode equation and PC1D solar cell simulations. The calculated device performance parameters are found to be consistent with direct current-voltage measurement demonstrating the validity of this technique for electrical transport property measurements of the semiconducting layers in complete Si solar cells. To the best of our knowledge, this is the first method that enables determination of both minority and majority carrier transport parameters in both active layers of the p-n junction in a complete solar cell.
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Affiliation(s)
- Prakash Uprety
- Wright Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH, 43606, USA
| | - Indra Subedi
- Wright Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH, 43606, USA
| | - Maxwell M Junda
- Wright Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH, 43606, USA
| | - Robert W Collins
- Wright Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH, 43606, USA
| | - Nikolas J Podraza
- Wright Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH, 43606, USA.
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13
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Pradhan P, Aryal P, Attygalle D, Ibdah AR, Koirala P, Li J, Bhandari KP, Liyanage GK, Ellingson RJ, Heben MJ, Marsillac S, Collins RW, Podraza NJ. Real Time Spectroscopic Ellipsometry Analysis of First Stage CuIn 1-xGa xSe₂ Growth: Indium-Gallium Selenide Co-Evaporation. MATERIALS 2018; 11:ma11010145. [PMID: 29337931 PMCID: PMC5793643 DOI: 10.3390/ma11010145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Revised: 01/10/2018] [Accepted: 01/10/2018] [Indexed: 11/16/2022]
Abstract
Real time spectroscopic ellipsometry (RTSE) has been applied for in-situ monitoring of the first stage of copper indium-gallium diselenide (CIGS) thin film deposition by the three-stage co-evaporation process used for fabrication of high efficiency thin film photovoltaic (PV) devices. The first stage entails the growth of indium-gallium selenide (In1-xGax)₂Se₃ (IGS) on a substrate of Mo-coated soda lime glass maintained at a temperature of 400 °C. This is a critical stage of CIGS deposition because a large fraction of the final film thickness is deposited, and as a result precise compositional control is desired in order to achieve the optimum performance of the resulting CIGS solar cell. RTSE is sensitive to monolayer level film growth processes and can provide accurate measurements of bulk and surface roughness layer thicknesses. These in turn enable accurate measurements of the bulk layer optical response in the form of the complex dielectric function ε = ε₁ - iε₂, spectra. Here, RTSE has been used to obtain the (ε₁, ε₂) spectra at the measurement temperature of 400 °C for IGS thin films of different Ga contents (x) deduced from different ranges of accumulated bulk layer thickness during the deposition process. Applying an analytical expression in common for each of the (ε₁, ε₂) spectra of these IGS films, oscillator parameters have been obtained in the best fits and these parameters in turn have been fitted with polynomials in x. From the resulting database of polynomial coefficients, the (ε₁, ε₂) spectra can be generated for any composition of IGS from the single parameter, x. The results have served as an RTSE fingerprint for IGS composition and have provided further structural information beyond simply thicknesses, for example information related to film density and grain size. The deduced IGS structural evolution and the (ε₁, ε₂) spectra have been interpreted as well in relation to observations from scanning electron microscopy, X-ray diffractometry and energy-dispersive X-ray spectroscopy profiling analyses. Overall the structural, optical and compositional analysis possible by RTSE has assisted in understanding the growth and properties of three stage CIGS absorbers for solar cells and shows future promise for enhancing cell performance through monitoring and control.
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Affiliation(s)
- Puja Pradhan
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
| | - Puruswottam Aryal
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
| | - Dinesh Attygalle
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
| | - Abdel-Rahman Ibdah
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
| | - Prakash Koirala
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
| | - Jian Li
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
| | - Khagendra P Bhandari
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
| | - Geethika K Liyanage
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
| | - Randy J Ellingson
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
| | - Michael J Heben
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
| | - Sylvain Marsillac
- Virginia Institute of Photovoltaics, Old Dominion University, Norfolk, VA 23529, USA.
| | - Robert W Collins
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
| | - Nikolas J Podraza
- Center for Photovoltaics Innovation and Commercialization & Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.
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14
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Huang X, Roth CB. Changes in the temperature-dependent specific volume of supported polystyrene films with film thickness. J Chem Phys 2017; 144:234903. [PMID: 27334190 DOI: 10.1063/1.4953855] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Recent studies have measured or predicted thickness-dependent shifts in density or specific volume of polymer films as a possible means of understanding changes in the glass transition temperature Tg(h) with decreasing film thickness with some experimental works claiming unrealistically large (25%-30%) increases in film density with decreasing thickness. Here we use ellipsometry to measure the temperature-dependent index of refraction of polystyrene (PS) films supported on silicon and investigate the validity of the commonly used Lorentz-Lorenz equation for inferring changes in density or specific volume from very thin films. We find that the density (specific volume) of these supported PS films does not vary by more than ±0.4% of the bulk value for film thicknesses above 30 nm, and that the small variations we do observe are uncorrelated with any free volume explanation for the Tg(h) decrease exhibited by these films. We conclude that the derivation of the Lorentz-Lorenz equation becomes invalid for very thin films as the film thickness approaches ∼20 nm, and that reports of large density changes greater than ±1% of bulk for films thinner than this likely suffer from breakdown in the validity of this equation or in the difficulties associated with accurately measuring the index of refraction of such thin films. For larger film thicknesses, we do observed small variations in the effective specific volume of the films of 0.4 ± 0.2%, outside of our experimental error. These shifts occur simultaneously in both the liquid and glassy regimes uniformly together starting at film thicknesses less than ∼120 nm but appear to be uncorrelated with Tg(h) decreases; possible causes for these variations are discussed.
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Affiliation(s)
- Xinru Huang
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA
| | - Connie B Roth
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA
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15
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Cho YJ, Chegal W, Lee JP, Cho HM. Universal evaluation of combined standard uncertainty for rotating-element spectroscopic ellipsometers. OPTICS EXPRESS 2016; 24:26215-26227. [PMID: 27857358 DOI: 10.1364/oe.24.026215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present for the first time a universal expression for the combined standard uncertainty for all types of rotating-element spectroscopic ellipsometers (RE-SEs). Specifically, we introduce general model functions as universal analytic expressions for the combined standard uncertainties of the ellipsometric sample parameters. The model functions are expressed as functions of influencing quantities that are not known exactly. The detailed expressions for the model functions are provided for the common RE-SEs. Our approach can be used for instrumentation, standardization, simulation, metrology, optimization of measurement conditions, and performance comparison between RE-SEs.
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16
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Subedi I, Bhandari KP, Ellingson RJ, Podraza NJ. Near infrared to ultraviolet optical properties of bulk single crystal and nanocrystal thin film iron pyrite. NANOTECHNOLOGY 2016; 27:295702. [PMID: 27285310 DOI: 10.1088/0957-4484/27/29/295702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report optical properties of iron pyrite (FeS2) determined from ex situ spectroscopic ellipsometry measurements made on both a commercially available bulk single crystal and nanocrystalline thin film over a spectral range of 0.735-5.887 eV. The complex dielectric function, ε (E) = ε 1 (E) + iε 2 (E), spectra have been determined by fitting a layered parametric model to the ellipsometric measurements. Spectra in ε are modeled using a Kramers-Kronig consistent critical point parabolic band model involving seven critical points for the bulk single crystal and four critical points for the nanocrystalline film. Absorption coefficient spectra for both types of samples are also determined from ε. Critical point features in the nanocrystalline films are broader, have lower amplitude and lower energy critical points detected having a small blue shift when compared to the single crystal sample.
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Affiliation(s)
- Indra Subedi
- Department of Physics and Astronomy & Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, OH 43606, USA
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17
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Spectroscopic Ellipsometry Studies of n- i- p Hydrogenated Amorphous Silicon Based Photovoltaic Devices. MATERIALS 2016; 9:ma9030128. [PMID: 28773255 PMCID: PMC5456701 DOI: 10.3390/ma9030128] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 02/12/2016] [Accepted: 02/18/2016] [Indexed: 11/16/2022]
Abstract
Optimization of thin film photovoltaics (PV) relies on characterizing the optoelectronic and structural properties of each layer and correlating these properties with device performance. Growth evolution diagrams have been used to guide production of materials with good optoelectronic properties in the full hydrogenated amorphous silicon (a-Si:H) PV device configuration. The nucleation and evolution of crystallites forming from the amorphous phase were studied using in situ near-infrared to ultraviolet spectroscopic ellipsometry during growth of films prepared as a function of hydrogen to reactive gas flow ratio R = [H₂]/[SiH₄]. In conjunction with higher photon energy measurements, the presence and relative absorption strength of silicon-hydrogen infrared modes were measured by infrared extended ellipsometry measurements to gain insight into chemical bonding. Structural and optical models have been developed for the back reflector (BR) structure consisting of sputtered undoped zinc oxide (ZnO) on top of silver (Ag) coated glass substrates. Characterization of the free-carrier absorption properties in Ag and the ZnO + Ag interface as well as phonon modes in ZnO were also studied by spectroscopic ellipsometry. Measurements ranging from 0.04 to 5 eV were used to extract layer thicknesses, composition, and optical response in the form of complex dielectric function spectra (ε = ε₁ + iε₂) for Ag, ZnO, the ZnO + Ag interface, and undoped a-Si:H layer in a substrate n-i-p a-Si:H based PV device structure.
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18
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Cho YJ, Chegal W, Lee JP, Cho HM. Universal evaluations and expressions of measuring uncertainty for rotating-element spectroscopic ellipsometers. OPTICS EXPRESS 2015; 23:16481-16491. [PMID: 26193619 DOI: 10.1364/oe.23.016481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We obtain the universal evaluations and expressions of measuring uncertainty for all types of rotating-element spectroscopic ellipsometers. We introduce a general data-reduction process to represent the universal analytic functions of the combined standard uncertainties of the ellipsometric sample parameters. To solve the incompleteness of the analytic expressions, we formulate the estimated covariance for the Fourier coefficient means extracted from the radiant flux waveform using a new Fourier analysis. Our approach can be used for optimization of measurement conditions, instrumentation, simulation, standardization, laboratory accreditation, and metrology.
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19
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Tyunina M, Yao L, Chvostova D, Dejneka A, Kocourek T, Jelinek M, Trepakov V, van Dijken S. Concurrent bandgap narrowing and polarization enhancement in epitaxial ferroelectric nanofilms. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2015; 16:026002. [PMID: 27877779 PMCID: PMC5036465 DOI: 10.1088/1468-6996/16/2/026002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/04/2015] [Indexed: 05/28/2023]
Abstract
Perovskite-type ferroelectric (FE) crystals are wide bandgap materials with technologically valuable optical and photoelectric properties. Here, versatile engineering of electronic transitions is demonstrated in FE nanofilms of KTaO3, KNbO3 (KNO), and NaNbO3 (NNO) with a thickness of 10-30 unit cells. Control of the bandgap is achieved using heteroepitaxial growth of new structural phases on SrTiO3 (001) substrates. Compared to bulk crystals, anomalous bandgap narrowing is obtained in the FE state of KNO and NNO films. This effect opposes polarization-induced bandgap widening, which is typically found for FE materials. Transmission electron microscopy and spectroscopic ellipsometry measurements indicate that the formation of higher-symmetry structural phases of KNO and NNO produces the desirable red shift of the absorption spectrum towards visible light, while simultaneously stabilizing robust FE order. Tuning of optical properties in FE films is of interest for nanoscale photonic and optoelectronic devices.
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Affiliation(s)
| | - Lide Yao
- NanoSpin, Department of Applied Physics, Aalto University School of Science, PO Box 15100, FI-00076 Aalto, Finland
| | - Dagmar Chvostova
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - Alexandr Dejneka
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - Tomas Kocourek
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - Miroslav Jelinek
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - Vladimir Trepakov
- Ioffe Physical-Technical Institute RAS, 194021 St. Petersburg, Russia
| | - Sebastiaan van Dijken
- NanoSpin, Department of Applied Physics, Aalto University School of Science, PO Box 15100, FI-00076 Aalto, Finland
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20
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Del Rosso T, Sánchez JEH, Carvalho RDS, Pandoli O, Cremona M. Accurate and simultaneous measurement of thickness and refractive index of thermally evaporated thin organic films by surface plasmon resonance spectroscopy. OPTICS EXPRESS 2014; 22:18914-18923. [PMID: 25320977 DOI: 10.1364/oe.22.018914] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We demonstrate that Surface Plasmon Resonance spectroscopy can be used for the accurate and simultaneous determination of the thickness and refractive index of transparent thin thermally deposited organic films. The experimental approach is based on a two-metal deposition or a two-thickness method. These methods have been applied to an encapsulated sample containing a thin film of commercial tris(8-hydroxyquinoline) (Alq3). The accuracy of the measurement depends on the control of the film deposition process and suggests the use of SPR spectroscopy as inexpensive and valuable metrology tool for small molecule organic thin films.
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21
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Kozbial A, Li Z, Conaway C, McGinley R, Dhingra S, Vahdat V, Zhou F, D'Urso B, Liu H, Li L. Study on the surface energy of graphene by contact angle measurements. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:8598-606. [PMID: 24983409 DOI: 10.1021/la5018328] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Because of the atomic thinness of graphene, its integration into a device will always involve its interaction with at least one supporting substrate, making the surface energy of graphene critical to its real-life applications. In the current paper, the contact angle of graphene synthesized by chemical vapor deposition (CVD) was monitored temporally after synthesis using water, diiodomethane, ethylene glycol, and glycerol. The surface energy was then calculated based on the contact angle data by the Fowkes, Owens-Wendt (extended Fowkes), and Neumann models. The surface energy of fresh CVD graphene grown on a copper substrate (G/Cu) immediately after synthesis was determined to be 62.2 ± 3.1 mJ/m(2) (Fowkes), 53.0 ± 4.3 mJ/m(2) (Owens-Wendt) and 63.8 ± 2.0 mJ/m(2) (Neumann), which decreased to 45.6 ± 3.9, 37.5 ± 2.3, and 57.4 ± 2.1 mJ/m(2), respectively, after 24 h of air exposure. The ellipsometry characterization indicates that the surface energy of G/Cu is affected by airborne hydrocarbon contamination. G/Cu exhibits the highest surface energy immediately after synthesis, and the surface energy decreases after airborne contamination occurs. The root cause of intrinsically mild polarity of G/Cu surface is discussed.
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Affiliation(s)
- Andrew Kozbial
- Department of Chemical & Petroleum Engineering, Swanson School of Engineering, ‡Department of Chemistry, §Department of Physics and Astronomy, and ∥Department of Mechanical Engineering & Materials Science, Swanson School of Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
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Chegal W, Lee JP, Cho HM, Han SW, Cho YJ. Optimizing the precision of a multichannel three-polarizer spectroscopic ellipsometer. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2013; 30:1310-1319. [PMID: 24323144 DOI: 10.1364/josaa.30.001310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We developed a multichannel three-polarizer spectroscopic ellipsometer based on a data acquisition algorithm for achieving optimized precision. This algorithm measures unnormalized Fourier coefficients accurately and precisely. Offset angles for optical elements were obtained as wavelength-independent values using regression calibration. Derived subsets of data reduction functions were used to calculate sample parameters. Correlation coefficients of Fourier coefficients were used to calculate errors in the sample parameters. Mean standard deviations of the sample parameters for each data reduction method were compared to identify the best method. This approach could be used to identify suitable precision optimization methods for other rotating-element ellipsometers.
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23
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Wormeester H, Kole PR, Poelsema B. Simultaneous characterization of detector and source imperfections in infrared ellipsometry. APPLIED OPTICS 2009; 48:2853-2859. [PMID: 19458734 DOI: 10.1364/ao.48.002853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Optical components required for infrared (IR) ellipsometry have distinctly worse characteristics compared to those available for the visible spectrum. The calibration of the optical components used is therefore essential for obtaining reliable results. Here a powerful method is outlined to calibrate simultaneously the polarization characteristics of a source and detector through the synchronous rotation of two polarizers. The performance of this method is to a large degree independent of the quality of (commercially available) polarizers. This renders this method robust and highly suitable for the IR range. Moreover, it is also inherently insensitive toward a nonlinear response of the detector. This enables us to use this method as the first step in the quantification of component imperfections.
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Affiliation(s)
- Herbert Wormeester
- Solid State Physics, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands.
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