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Title: Electronic structure and Schottky-barrier formation on GaAs (100) surfaces prepared by thermal desorption of a protective arsenic coating

Abstract

Soft-x-ray photoemission spectroscopy has been used to characterize GaAs(100) surfaces and interfaces grown by molecular-beam epitaxy and prepared by the thermal desorption of a protective As coating. The samples studied were grown and arsenic capped identically to those used in a previous study (Brillson {ital et} {ital al}., J. Vac. Sci. Technol. B 6, 1263 (1988)). In this previous work, unpinned'' Schottky-barrier formation was reported, with barrier heights over a wide (0.75-eV) range. This is a striking result, as it was previously believed that all metals will pin GaAs surfaces in a narrow energy range near the middle of the band gap. This large range of barrier heights later led to the suggestion that the (100) surface could become an insulating layer that could screen out the effects of metal-induced gap states. Motivated by this work, we have studied Al and Au Schottky barriers since the deposition of these two metals gave the extreme low and high barriers in the 0.75-eV range. We have also characterized the clean surfaces prepared by desorbing the As caps at different temperatures. The As 3{ital d} and Ga 3{ital d} core levels showed that the surface stoichiometry could be varied significantly with the desorptionmore » temperature. The As 3{ital d} line shape was found to be the best indication of the surface stoichiometry after the anneal. The valence-band spectra did not show any strong features which could be used to determine when the sample was completely decapped. The electronic structure of the surface layer was investigated experimentally, and no evidence of an insulating reconstruction was found. In our study of band bending, we found that the low-doped samples used here and in the earlier study showed significant photovoltages resulting in incorrect band-bending measurements. We also found that the Au measurements are made difficult by the presence of core-level shifts due to Au-Ga alloying.« less

Authors:
; ; ; ; ; ;  [1];  [2]
  1. Stanford Electronics Laboratories, Stanford University, Stanford, California 94305-4055 (United States)
  2. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
Publication Date:
OSTI Identifier:
7237711
DOE Contract Number:  
AC02-76CH00016
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter; (United States)
Additional Journal Information:
Journal Volume: 45:19; Journal ID: ISSN 0163-1829
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; GALLIUM ARSENIDES; ELECTRONIC STRUCTURE; SCHOTTKY BARRIER DIODES; SURFACE PROPERTIES; THIN FILMS; ARSENIC COMPOUNDS; ARSENIDES; FILMS; GALLIUM COMPOUNDS; PNICTIDES; SEMICONDUCTOR DEVICES; SEMICONDUCTOR DIODES; 360605* - Materials- Radiation Effects

Citation Formats

Spindt, C J, Yamada, M, Meissner, P L, Miyano, K E, Kendelewicz, T, Herrera-Gomez, A, Spicer, W E, and Arko, A J. Electronic structure and Schottky-barrier formation on GaAs (100) surfaces prepared by thermal desorption of a protective arsenic coating. United States: N. p., 1992. Web. doi:10.1103/PhysRevB.45.11108.
Spindt, C J, Yamada, M, Meissner, P L, Miyano, K E, Kendelewicz, T, Herrera-Gomez, A, Spicer, W E, & Arko, A J. Electronic structure and Schottky-barrier formation on GaAs (100) surfaces prepared by thermal desorption of a protective arsenic coating. United States. https://doi.org/10.1103/PhysRevB.45.11108
Spindt, C J, Yamada, M, Meissner, P L, Miyano, K E, Kendelewicz, T, Herrera-Gomez, A, Spicer, W E, and Arko, A J. Fri . "Electronic structure and Schottky-barrier formation on GaAs (100) surfaces prepared by thermal desorption of a protective arsenic coating". United States. https://doi.org/10.1103/PhysRevB.45.11108.
@article{osti_7237711,
title = {Electronic structure and Schottky-barrier formation on GaAs (100) surfaces prepared by thermal desorption of a protective arsenic coating},
author = {Spindt, C J and Yamada, M and Meissner, P L and Miyano, K E and Kendelewicz, T and Herrera-Gomez, A and Spicer, W E and Arko, A J},
abstractNote = {Soft-x-ray photoemission spectroscopy has been used to characterize GaAs(100) surfaces and interfaces grown by molecular-beam epitaxy and prepared by the thermal desorption of a protective As coating. The samples studied were grown and arsenic capped identically to those used in a previous study (Brillson {ital et} {ital al}., J. Vac. Sci. Technol. B 6, 1263 (1988)). In this previous work, unpinned'' Schottky-barrier formation was reported, with barrier heights over a wide (0.75-eV) range. This is a striking result, as it was previously believed that all metals will pin GaAs surfaces in a narrow energy range near the middle of the band gap. This large range of barrier heights later led to the suggestion that the (100) surface could become an insulating layer that could screen out the effects of metal-induced gap states. Motivated by this work, we have studied Al and Au Schottky barriers since the deposition of these two metals gave the extreme low and high barriers in the 0.75-eV range. We have also characterized the clean surfaces prepared by desorbing the As caps at different temperatures. The As 3{ital d} and Ga 3{ital d} core levels showed that the surface stoichiometry could be varied significantly with the desorption temperature. The As 3{ital d} line shape was found to be the best indication of the surface stoichiometry after the anneal. The valence-band spectra did not show any strong features which could be used to determine when the sample was completely decapped. The electronic structure of the surface layer was investigated experimentally, and no evidence of an insulating reconstruction was found. In our study of band bending, we found that the low-doped samples used here and in the earlier study showed significant photovoltages resulting in incorrect band-bending measurements. We also found that the Au measurements are made difficult by the presence of core-level shifts due to Au-Ga alloying.},
doi = {10.1103/PhysRevB.45.11108},
url = {https://www.osti.gov/biblio/7237711}, journal = {Physical Review, B: Condensed Matter; (United States)},
issn = {0163-1829},
number = ,
volume = 45:19,
place = {United States},
year = {1992},
month = {5}
}