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Electronic structure of epitaxial β-FeSi2 on Si(111)
A317 Surface Science 251/252 (1991) 175-179 North-Holland
175
Electronic structure of epitaxial B-FeSi 2 on S i ( l l l ) M. De Crescenzi, G. Gaggiotti, N. Motta, F. Patella, A. Balzarotti Dipartirnento di Fisica, H Universitd di Rorna, 00173 Roma, Italy
G. Mattogno lstituto di Teoria e Struttura Elettronica del CNR, Area della Ricerca di Roma, Monterotondo Stazione, 00016 Roma, Italy
and J. Derrien Centre de Recherche sur les Mecanismes de la Croissance Cristalline-CNRS, Campus Luminy, 13288 Marseille, France Received 1 October 1990; accepted for publication 16 December 1990 We have applied a combination of surface spectroscopy techniques (XPS, Auger, electron energy loss and bremsstrahlung isochromat spectroscopy) to investigate the chemical bonding of/~-FeSi 2 thin films epitaxially grown on the Si(lll) surface. The local structure of the films has been investigated with the extended BIS fine structure technique. The semiconducting nature of the films is evidenced by a shift of the empty d-band to higher binding energies and by the lowering of the density of the states close to E F as compared to pure Fe films. The dielectric functions extracted from the electron energy loss spectra strongly support this picture. We measured an energy gap of 1.0 5:0.2 eV which compares favourably with density of states calculations for the fl-FeSi 2 semiconducting phase.
180
Surface Science 251/252 (1991) 180-184 North-Holland
Emissivity as a method of surfaces and thin films analysis P. Pigeat, N. Pacia and B. Weber Laboratoire de Science et Gdnie des Surfaces (URA CNRS 1402), Ecole des Mines, Parc de Saurupt, 54042 Nancy Cedex, France Received 1 October 1990; accepted for publication 30 November 1990 Limited to the field of pyrometry, the observation of thermal radiation has never been really used as a source of information for the characterization of material surface. An IR spectrometry technique which is briefly described has been conceived in order to study the influence of surface physico-chemical parameters on the directional and spectral emissivity (cx0) of materials. One of these apparatus has been set up on a conventional UHV system equipped with AES and SIMS. The variation (Ac/c)x 0 is recorded in situ during the evolution of a surface parameter. The examples shown are platinum deposit on graphite by vapour condensation, growth of an oxide film on metal, growth of homogeneous or inhomogeneous films, influence of the crystalline phase transition of a deposit, etc. For each case, an optical theoretical description has been carried out. From the comparison with other observations (electron microscopy, X-ray diffraction, AES and kinetic measurements), it is shown how the observation of (At)x0 enables us to obtain information on parameters such as the number, the shape or the orientation of islands in granular deposits, the crystal structure, the porosity of a film or the failure critical thickness of a coating.
Surface Science 251/252 (1991) 185-190 North-Holland
185
X-ray standing wave analysis of the G a A s / S i interface Tomoaki Kawamura a, Yukio Fukuda b, Masaharu Oshima a, Yoshiro Ohmachi b, Koichi Izumi c, Keiichi Hirano c, Tetsuya Ishikawa ~ and Seishi Kikuta ~ a N T T Applied Electronics Laboratories, Midori-cho, Musashino, Tokyo 180, Japan b N T T Optoelectronics Laboratories, Wakamiya, Morinosato, Atsugi, Kanagawa 243-01, Japan c Faculty of Engineering University of Tokyo, Hongo, Bunkyo, Tokyo 113, Japan Received 1 October 1990; accepted for publication 21 December 1990 The X-ray standing wave method, an interferometric technique for accurately determining the position of atoms at surfaces and interfaces, allows us to determine the position of atoms along the diffraction vector. In spite of the validity of the X-ray standing wave method, there are few analyses of buried hetero epitaxial interface structure of semiconductors because of the signal adding
175
Electronic structure of epitaxial B-FeSi 2 on S i ( l l l ) M. De Crescenzi, G. Gaggiotti, N. Motta, F. Patella, A. Balzarotti Dipartirnento di Fisica, H Universitd di Rorna, 00173 Roma, Italy
G. Mattogno lstituto di Teoria e Struttura Elettronica del CNR, Area della Ricerca di Roma, Monterotondo Stazione, 00016 Roma, Italy
and J. Derrien Centre de Recherche sur les Mecanismes de la Croissance Cristalline-CNRS, Campus Luminy, 13288 Marseille, France Received 1 October 1990; accepted for publication 16 December 1990 We have applied a combination of surface spectroscopy techniques (XPS, Auger, electron energy loss and bremsstrahlung isochromat spectroscopy) to investigate the chemical bonding of/~-FeSi 2 thin films epitaxially grown on the Si(lll) surface. The local structure of the films has been investigated with the extended BIS fine structure technique. The semiconducting nature of the films is evidenced by a shift of the empty d-band to higher binding energies and by the lowering of the density of the states close to E F as compared to pure Fe films. The dielectric functions extracted from the electron energy loss spectra strongly support this picture. We measured an energy gap of 1.0 5:0.2 eV which compares favourably with density of states calculations for the fl-FeSi 2 semiconducting phase.
180
Surface Science 251/252 (1991) 180-184 North-Holland
Emissivity as a method of surfaces and thin films analysis P. Pigeat, N. Pacia and B. Weber Laboratoire de Science et Gdnie des Surfaces (URA CNRS 1402), Ecole des Mines, Parc de Saurupt, 54042 Nancy Cedex, France Received 1 October 1990; accepted for publication 30 November 1990 Limited to the field of pyrometry, the observation of thermal radiation has never been really used as a source of information for the characterization of material surface. An IR spectrometry technique which is briefly described has been conceived in order to study the influence of surface physico-chemical parameters on the directional and spectral emissivity (cx0) of materials. One of these apparatus has been set up on a conventional UHV system equipped with AES and SIMS. The variation (Ac/c)x 0 is recorded in situ during the evolution of a surface parameter. The examples shown are platinum deposit on graphite by vapour condensation, growth of an oxide film on metal, growth of homogeneous or inhomogeneous films, influence of the crystalline phase transition of a deposit, etc. For each case, an optical theoretical description has been carried out. From the comparison with other observations (electron microscopy, X-ray diffraction, AES and kinetic measurements), it is shown how the observation of (At)x0 enables us to obtain information on parameters such as the number, the shape or the orientation of islands in granular deposits, the crystal structure, the porosity of a film or the failure critical thickness of a coating.
Surface Science 251/252 (1991) 185-190 North-Holland
185
X-ray standing wave analysis of the G a A s / S i interface Tomoaki Kawamura a, Yukio Fukuda b, Masaharu Oshima a, Yoshiro Ohmachi b, Koichi Izumi c, Keiichi Hirano c, Tetsuya Ishikawa ~ and Seishi Kikuta ~ a N T T Applied Electronics Laboratories, Midori-cho, Musashino, Tokyo 180, Japan b N T T Optoelectronics Laboratories, Wakamiya, Morinosato, Atsugi, Kanagawa 243-01, Japan c Faculty of Engineering University of Tokyo, Hongo, Bunkyo, Tokyo 113, Japan Received 1 October 1990; accepted for publication 21 December 1990 The X-ray standing wave method, an interferometric technique for accurately determining the position of atoms at surfaces and interfaces, allows us to determine the position of atoms along the diffraction vector. In spite of the validity of the X-ray standing wave method, there are few analyses of buried hetero epitaxial interface structure of semiconductors because of the signal adding