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Leroy F, El Barraj A, Cheynis F, Müller P, Curiotto S. Determination of the Thermomigration Force on Adatoms. PHYSICAL REVIEW LETTERS 2023; 131:116202. [PMID: 37774294 DOI: 10.1103/physrevlett.131.116202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 05/24/2023] [Accepted: 07/12/2023] [Indexed: 10/01/2023]
Abstract
Thermal gradients in nanomaterials can cause surface mass transport phenomena. However, the atomic fluxes are challenging to quantify and the underlying atomic mechanisms are complex. Using low energy electron microscopy we have examined in operando, under a thermal gradient of 10^{4} K/m, the thermomigration of supercooled Si(111)-1×1 advacancy islands. The islands move in the direction of the thermal gradient at 0.26±0.06 nm/s. This reveals that the adatoms move toward the cold region and the effective force exerted on Si adatoms is 1.4±0.4×10^{-8} eV/nm. We quantify the heat of transport of Si atoms Q^{*}=1.2±0.4 eV and show that it corresponds to the combined effects of adatom creation at step edges and adatom diffusion on atomically flat terraces.
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Affiliation(s)
- F Leroy
- Aix Marseille Univ, CNRS, CINAM, AMUTECH, Marseille, France
| | - A El Barraj
- Aix Marseille Univ, CNRS, CINAM, AMUTECH, Marseille, France
| | - F Cheynis
- Aix Marseille Univ, CNRS, CINAM, AMUTECH, Marseille, France
| | - P Müller
- Aix Marseille Univ, CNRS, CINAM, AMUTECH, Marseille, France
| | - S Curiotto
- Aix Marseille Univ, CNRS, CINAM, AMUTECH, Marseille, France
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Colin J, Jamnig A, Furgeaud C, Michel A, Pliatsikas N, Sarakinos K, Abadias G. In Situ and Real-Time Nanoscale Monitoring of Ultra-Thin Metal Film Growth Using Optical and Electrical Diagnostic Tools. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2225. [PMID: 33182409 PMCID: PMC7697846 DOI: 10.3390/nano10112225] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 01/08/2023]
Abstract
Continued downscaling of functional layers for key enabling devices has prompted the development of characterization tools to probe and dynamically control thin film formation stages and ensure the desired film morphology and functionalities in terms of, e.g., layer surface smoothness or electrical properties. In this work, we review the combined use of in situ and real-time optical (wafer curvature, spectroscopic ellipsometry) and electrical probes for gaining insights into the early growth stages of magnetron-sputter-deposited films. Data are reported for a large variety of metals characterized by different atomic mobilities and interface reactivities. For fcc noble-metal films (Ag, Cu, Pd) exhibiting a pronounced three-dimensional growth on weakly-interacting substrates (SiO2, amorphous carbon (a-C)), wafer curvature, spectroscopic ellipsometry, and resistivity techniques are shown to be complementary in studying the morphological evolution of discontinuous layers, and determining the percolation threshold and the onset of continuous film formation. The influence of growth kinetics (in terms of intrinsic atomic mobility, substrate temperature, deposition rate, deposition flux temporal profile) and the effect of deposited energy (through changes in working pressure or bias voltage) on the various morphological transition thicknesses is critically examined. For bcc transition metals, like Fe and Mo deposited on a-Si, in situ and real-time growth monitoring data exhibit transient features at a critical layer thickness of ~2 nm, which is a fingerprint of an interface-mediated crystalline-to-amorphous phase transition, while such behavior is not observed for Ta films that crystallize into their metastable tetragonal β-Ta allotropic phase. The potential of optical and electrical diagnostic tools is also explored to reveal complex interfacial reactions and their effect on growth of Pd films on a-Si or a-Ge interlayers. For all case studies presented in the article, in situ data are complemented with and benchmarked against ex situ structural and morphological analyses.
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Affiliation(s)
- Jonathan Colin
- Institut Pprime, UPR 3346, CNRS-Université de Poitiers-ENSMA, 11 Boulevard Marie et Pierre Curie, TSA 41123, CEDEX 9, 86073 Poitiers, France; (J.C.); (A.J.); (C.F.); (A.M.)
| | - Andreas Jamnig
- Institut Pprime, UPR 3346, CNRS-Université de Poitiers-ENSMA, 11 Boulevard Marie et Pierre Curie, TSA 41123, CEDEX 9, 86073 Poitiers, France; (J.C.); (A.J.); (C.F.); (A.M.)
- Nanoscale Engineering Division, Department of Physics, Chemistry and Biology, Linköping University, SE 581 83 Linköping, Sweden;
| | - Clarisse Furgeaud
- Institut Pprime, UPR 3346, CNRS-Université de Poitiers-ENSMA, 11 Boulevard Marie et Pierre Curie, TSA 41123, CEDEX 9, 86073 Poitiers, France; (J.C.); (A.J.); (C.F.); (A.M.)
| | - Anny Michel
- Institut Pprime, UPR 3346, CNRS-Université de Poitiers-ENSMA, 11 Boulevard Marie et Pierre Curie, TSA 41123, CEDEX 9, 86073 Poitiers, France; (J.C.); (A.J.); (C.F.); (A.M.)
| | - Nikolaos Pliatsikas
- Nanoscale Engineering Division, Department of Physics, Chemistry and Biology, Linköping University, SE 581 83 Linköping, Sweden;
| | - Kostas Sarakinos
- Nanoscale Engineering Division, Department of Physics, Chemistry and Biology, Linköping University, SE 581 83 Linköping, Sweden;
| | - Gregory Abadias
- Institut Pprime, UPR 3346, CNRS-Université de Poitiers-ENSMA, 11 Boulevard Marie et Pierre Curie, TSA 41123, CEDEX 9, 86073 Poitiers, France; (J.C.); (A.J.); (C.F.); (A.M.)
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Cheynis F, Curiotto S, Leroy F, Müller P. Spatial inhomogeneity and temporal dynamics of a 2D electron gas in interaction with a 2D adatom gas. Sci Rep 2017; 7:10642. [PMID: 28878360 PMCID: PMC5587567 DOI: 10.1038/s41598-017-10300-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 08/07/2017] [Indexed: 11/09/2022] Open
Abstract
Fundamental interest for 2D electron gas (2DEG) systems has been recently renewed with the advent of 2D materials and their potential high-impact applications in optoelectronics. Here, we investigate a 2DEG created by the electron transfer from a Ag adatom gas deposited on a Si(111) \documentclass[12pt]{minimal}
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\begin{document}$$\sqrt{{\bf{3}}}{\boldsymbol{\times }}\sqrt{{\bf{3}}}$$\end{document}3×3-Ag surface to an electronic surface state. Using low-energy electron microscopy (LEEM), we measure the Ag adatom gas concentration and the 2DEG-induced charge transfer. We demonstrate a linear dependence of the surface work function change on the Ag adatom gas concentration. A breakdown of the linear relationship is induced by the occurrence of the Ag adatom gas superstructure identified as Si(111) \documentclass[12pt]{minimal}
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\begin{document}$$\sqrt{{\bf{21}}}{\boldsymbol{\times }}\sqrt{{\bf{21}}}$$\end{document}21×21-Ag only observed below room temperature. We evidence below room temperature a confinement of the 2DEG on atomic terraces characterised by spatial inhomogeneities of the 2DEG-induced charge transfer along with temporal fluctuations. These variations mirror the Ag adatom gas concentration changes induced by the growth of 3D Ag islands and the occurrence of an Ehrlich-Schwoebel diffusion barrier of 155 ± 10 meV.
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Affiliation(s)
- F Cheynis
- Aix Marseille Univ, CNRS, CINAM, Marseille, France.
| | - S Curiotto
- Aix Marseille Univ, CNRS, CINAM, Marseille, France
| | - F Leroy
- Aix Marseille Univ, CNRS, CINAM, Marseille, France
| | - P Müller
- Aix Marseille Univ, CNRS, CINAM, Marseille, France
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Marquardt C, Paulheim A, Rohbohm N, Merkel R, Sokolowski M. A surface science compatible epifluorescence microscope for inspection of samples under ultra high vacuum and cryogenic conditions. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:083702. [PMID: 28863709 DOI: 10.1063/1.4997953] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We modified an epi-illumination light microscope and mounted it on an ultra high vacuum chamber for investigating samples used in a surface science experiment. For easy access and bake out, all optical components are placed outside the vacuum and the sample is imaged through a glass window. The microscope can be operated in reflection brightfield or epifluorescence mode to image the sample surface or fluorescent dye molecules adsorbed on it. The homemade sample mounting was made compatible for the use under the microscope; sample temperatures as low as 6 K can be achieved. The performance of the microscope is demonstrated on two model samples: Brightfield-images of a well-prepared Ag(100) surface show a macroscopic corrugation of the surface, although low energy electron diffraction data indicate a highly ordered crystalline surface. The surface shows macroscopic protrusions with flat regions, about 20-200 μm in diameter, in between. Fluorescence images of diluted 3,4,9,10-perylene tetracarboxylicacid dianhydride (PTCDA) molecules adsorbed on an ultrathin epitaxial KCl film on the Ag(100) surface show a shading effect at surface protrusions due to an inclined angle of incidence of the PTCDA beam during deposition. For some preparations, the distribution of the fluorescence intensity is inhomogeneous and shows a dense network of bright patches about 5 μm in diameter related to the macroscopic corrugation of the surface. We propose that such a light microscope can aid many surface science experiments, especially those dealing with epitaxial growth or fluorescent materials.
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Affiliation(s)
- Christian Marquardt
- Institut für Physikalische und Theoretische Chemie der Universität Bonn, Wegelerstrasse 12, 53115 Bonn, Germany
| | - Alexander Paulheim
- Institut für Physikalische und Theoretische Chemie der Universität Bonn, Wegelerstrasse 12, 53115 Bonn, Germany
| | - Nils Rohbohm
- Institut für Physikalische und Theoretische Chemie der Universität Bonn, Wegelerstrasse 12, 53115 Bonn, Germany
| | - Rudolf Merkel
- Institute of Complex Systems, ICS-7: Biomechanics, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Moritz Sokolowski
- Institut für Physikalische und Theoretische Chemie der Universität Bonn, Wegelerstrasse 12, 53115 Bonn, Germany
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Curiotto S, Leroy F, Cheynis F, Müller P. In-Plane Si Nanowire Growth Mechanism in Absence of External Si Flux. NANO LETTERS 2015; 15:4788-4792. [PMID: 26035081 DOI: 10.1021/acs.nanolett.5b01880] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report on a new mechanism of nanowire formation: during Au deposition on Si(110) substrates, Au-Si droplets grow, move spontaneously, and fabricate a Si nanowire behind them in the absence of Si external flux. Nanowires are formed by Si dissolved from the substrate at the advancing front of the droplets and transported backward to the crystallization front. The droplet shape is determined by the Si etching anisotropy. The nanowire formation can be tuned by changing experimental parameters like substrate temperature and Au deposition rate.
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Affiliation(s)
- Stefano Curiotto
- Aix Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille, France
| | - Frédéric Leroy
- Aix Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille, France
| | - Fabien Cheynis
- Aix Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille, France
| | - Pierre Müller
- Aix Marseille Université, CNRS, CINaM UMR 7325, 13288 Marseille, France
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