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Photofield emission spectroscopy of the tungsten <112> band structure
A203 100
Surface Science 247 (1991) 100-105 North-Holland
Surface band structure of CdTe(111)-2 × 2 by angle-resolved photoemission C. Janowitz, R. Manzke, M. Skibowski lnstitut fiir Experimentalph.vsik, Universitiit Kiel, W-2300 Kiel, German)'
and B.A. Orlowski Institute of Physics, Pohsh Academy of Sciences, 02668 Warsaw, Poland Received 21 May 1990; accepted for publication 25 May 1990 The surface band structure of non-cleavable C d T e ( l l l ) - 2 × 2 reconstructed surfaces is determined by means of angle-resolved photoemission and constant-final-state (CFS) spectroscopy. The experiments were performed with He I radiation and synchrotron radiation from the DORIS 1I storage ring at HASYLAB. High-quality (111)-2 × 2 surfaces were prepared by sputtering and annealing controlled by electron diffraction (LEED and RHEED). In order to distinguish between surface and bulk related emissions in the spectra we utilized, besides the criteria that the kll dispersion of surface states should reveal the 2 × 2 periodicity of the surface mesh, also photon energy dependent CFS series at several critical points of the surface Brillouin zone. The data on CdTe(111) will be compared with experimental and theoretical results which are available for the electronically similar G a A s ( l 11) surface.
106
Surface Science 247 (1991 ) 106-110 North-Holland
Photofield emission spectroscopy of the tungsten/112) band structure T. Radoh and S. Jask61ka Institute of Experimental Physics, University of Wroctaw, ul. Cybulskiego 36, 50-205 Wroctaw. Poland Received 1 July 1990; accepted for publication 30 July 1990 Optical transitions in photofield emission (PFE) characteristics from the (112) plane of tungsten have been observed at five values of photon energy in the visible range. To measure very small PFE currents modulated laser radiation and phase-sensitive detection have been used. Shoulders in the characteristics obtained with s-polarized light correspond to transitions in the bulk band structure near the Fermi level in accordance with the theoretical results of Christensen and Feuerbacher [1]. Using p-polarized light, peaks of the surface density of states, lying below the Fermi level, were observed in a good agreement with both the field and photofield emission distributions.
Surface Science 247 (1991) 111-114 North-Holland
111
Electron density near clean and alkali covered semiconductor surfaces G. Bigun and Yu. Suchorski Department of Physics, Technical University of Lviv, Mira St. 12, 290646 Lviv, USSR Received 21 May 1990; accepted for publication 16 July 1990 The electron density near clean and alkali-covered semiconductor surfaces is calculated using the exact relationship between the electrostatic potential of an adsystem and the exchange-correlation energy of the semiconductor substrate. The change in the work-function of a semiconductor surface as a function of the alkali adatom concentration is predicted on the basis of the calculated electron density. The inclusion of Coulomb correlation in this system makes it possible to obtain a more realistic description of the variation of the semiconductor surface properties with alkali adsorption.
Surface Science 247 (1991) 100-105 North-Holland
Surface band structure of CdTe(111)-2 × 2 by angle-resolved photoemission C. Janowitz, R. Manzke, M. Skibowski lnstitut fiir Experimentalph.vsik, Universitiit Kiel, W-2300 Kiel, German)'
and B.A. Orlowski Institute of Physics, Pohsh Academy of Sciences, 02668 Warsaw, Poland Received 21 May 1990; accepted for publication 25 May 1990 The surface band structure of non-cleavable C d T e ( l l l ) - 2 × 2 reconstructed surfaces is determined by means of angle-resolved photoemission and constant-final-state (CFS) spectroscopy. The experiments were performed with He I radiation and synchrotron radiation from the DORIS 1I storage ring at HASYLAB. High-quality (111)-2 × 2 surfaces were prepared by sputtering and annealing controlled by electron diffraction (LEED and RHEED). In order to distinguish between surface and bulk related emissions in the spectra we utilized, besides the criteria that the kll dispersion of surface states should reveal the 2 × 2 periodicity of the surface mesh, also photon energy dependent CFS series at several critical points of the surface Brillouin zone. The data on CdTe(111) will be compared with experimental and theoretical results which are available for the electronically similar G a A s ( l 11) surface.
106
Surface Science 247 (1991 ) 106-110 North-Holland
Photofield emission spectroscopy of the tungsten/112) band structure T. Radoh and S. Jask61ka Institute of Experimental Physics, University of Wroctaw, ul. Cybulskiego 36, 50-205 Wroctaw. Poland Received 1 July 1990; accepted for publication 30 July 1990 Optical transitions in photofield emission (PFE) characteristics from the (112) plane of tungsten have been observed at five values of photon energy in the visible range. To measure very small PFE currents modulated laser radiation and phase-sensitive detection have been used. Shoulders in the characteristics obtained with s-polarized light correspond to transitions in the bulk band structure near the Fermi level in accordance with the theoretical results of Christensen and Feuerbacher [1]. Using p-polarized light, peaks of the surface density of states, lying below the Fermi level, were observed in a good agreement with both the field and photofield emission distributions.
Surface Science 247 (1991) 111-114 North-Holland
111
Electron density near clean and alkali covered semiconductor surfaces G. Bigun and Yu. Suchorski Department of Physics, Technical University of Lviv, Mira St. 12, 290646 Lviv, USSR Received 21 May 1990; accepted for publication 16 July 1990 The electron density near clean and alkali-covered semiconductor surfaces is calculated using the exact relationship between the electrostatic potential of an adsystem and the exchange-correlation energy of the semiconductor substrate. The change in the work-function of a semiconductor surface as a function of the alkali adatom concentration is predicted on the basis of the calculated electron density. The inclusion of Coulomb correlation in this system makes it possible to obtain a more realistic description of the variation of the semiconductor surface properties with alkali adsorption.