Au and Al Schottky barrier formation on GaAs (100) surfaces prepared by thermal desorption of a protective arsenic coating

Conference · Tue Jan 01 04:00:00 EST 1991

OSTI ID:6187096

Spindt, C J; Yamada, M; Meissner, P L; Miyano, K E; Herrera, A; Spicer, W E ^[1]; Arko, A J ^[2]; Woodall, J M; Pettit, G D ^[3]

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1. Stanford Univ., CA (United States). Stanford Electronics Labs.
2. Los Alamos National Lab., NM (United States)
3. International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center

Photoelectron spectroscopy has been used as a tool to investigate the initial stages of Schottky barrier formation on GaAs (100) surfaces. This is a popular technique that has been used by many researchers in the past to measure the band bending (or shift) of the valence band and conduction band (a measure of the Schottky barrier shift), while the Fermi level remains fixed at the system ground (i.e., the ground of the spectrometer). Metal deposition on a semiconductor surface can alter the Schottky barrier at the surface and pin the Fermi level near the middle of the energy gap. Extremely clean and crystallographically perfect surfaces are required in this study. Toward this end, a method of protecting the GaAs surface was employed which consists of capping the GaAs surface with a layer of As. Upon introduction into the high vacuum system the As is thermally desorbed, revealing a pure GaAs surface. Our work was motivated by a previous study (Brillson et al) on similarly capped specimens, which suggested that metal overlayers do not pin the Schottky barrier in GaAs. Barrier heights varied by as much as 0.75 eV between Al and Au overlayers. This large energy range is a striking result in view of the fact that a considerable number of prior studies on both (110) and (100) surfaces have found that all metals will pin within a narrow (0.25 eV) range at midgap. We repeated the measurements of Brillson on the identically doped samples used in their study using two extreme range metals of Au and Al as overlayers. We found that the barrier height measurements on low doped n-type samples used in this work and in the previous work are affected by photovoltaic effects, even at room temperature. This was determined from taking spectra at a number of temperatures between 20 K and room temperature and looking for shifts. 16 refs., 7 figs.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: DOE; DOD; USDOE, Washington, DC (United States); Department of Defense, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6187096
• Report Number(s): LA-UR-91-3257; CONF-910115--1; ON: DE92002456
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation & Manufacture
42 ENGINEERING
426000 -- Engineering-- Components
Electron Devices & Circuits-- (1990-)
ALUMINIUM
ARSENIC
ARSENIC COMPOUNDS
ARSENIDES
COATINGS
DEPOSITION
DESORPTION
ELECTRON SPECTROSCOPY
ELEMENTS
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
GOLD
METALS
PHOTOELECTROMAGNETIC EFFECTS
PHOTOELECTRON SPECTROSCOPY
PHOTOVOLTAIC EFFECT
PNICTIDES
SCHOTTKY BARRIER DIODES
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SEMIMETALS
SPECTROSCOPY
SURFACES
TRANSITION ELEMENTS