Schottky barrier height control at epitaxial NiAl/GaAs(001) interfaces by means of variable band gap interlayers

Journal Article · Thu Jul 01 00:00:00 EDT 1993 · Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States)

DOI:https://doi.org/10.1116/1.578318· OSTI ID:6048261

Chambers, S A ^[1]

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1. Molecular Science Research Center, Pacific Northwest Laboratory, Richland, Washington 99352 (United States)

This article discusses recent developments in the use of semiconducting interlayers to tailor the Schottky barrier height (SBH) at a metal/GaAs interface. We have used AlAs, GaSe[sub [ital x]]As[sub 1[minus][ital x]], [ital n][sup ++]-Ge, and [ital n][sup ++]-Si interlayers between [ital n]- and [ital p]-GaAs(001) substrates and epitaxial NiAl metallic overlayers to see if a variable SBH is achievable. The interlayers were grown by molecular beam epitaxy and metal organic chemical vapor deposition, while the NiAl overlayers were grown by molecular beam epitaxy. X-ray photoelectron spectroscopy was used to follow the chemistry of interface formation, as well as band offsets and SBH values. Low-energy electron diffraction and x-ray photoelectron diffraction were used to determine structural properties of both the interlayer and overlayer. It was found that thermally stable SBH values ranging from [similar to]0.5 eV for [ital n][sup ++]-Si interlayers to [similar to]1.2 eV for AlAs interlayers are readily achievable on [ital n]-GaAs. Different mechanisms were found to be responsible for these two extrema in the SBH. For instance, charge transfer from the [ital n][sup ++]-Si interlayer to the depletion region of the substrate was found to compensate the space-charge region, thereby lowering the band bending and the resulting SBH. In contrast, Fermi-level pinning rather deep in the gap, combined with a substantial conduction band offset at the heterojunction, created a high SBH when AlAs interlayers were used. [ital n][sup ++]-Ge interlayers, while causing a similar SBH reduction as [ital n][sup ++]-Si were not found to be thermally stable. Disruption of the anion sublattice and Fermi-level pinning deep in the gap nullified the band flattening effect of the GaSe[sub [ital x]]As[sub 1[minus][ital x]] interlayer.

• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6048261
• Journal Information: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States), Vol. 11:4; ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
SEMICONDUCTOR JUNCTIONS
POTENTIALS
ALUMINIUM ALLOYS
ALUMINIUM ARSENIDES
FERMI LEVEL
GALLIUM ARSENIDES
GALLIUM SELENIDES
GERMANIUM
LAYERS
MOLECULAR BEAM EPITAXY
NICKEL ALLOYS
PHOTOELECTRON SPECTROSCOPY
SILICON
X RADIATION
ALLOYS
ALUMINIUM COMPOUNDS
ARSENIC COMPOUNDS
ARSENIDES
CHALCOGENIDES
ELECTROMAGNETIC RADIATION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY LEVELS
EPITAXY
GALLIUM COMPOUNDS
IONIZING RADIATIONS
JUNCTIONS
METALS
PNICTIDES
RADIATIONS
SELENIDES
SELENIUM COMPOUNDS
SEMIMETALS
SPECTROSCOPY
360606* - Other Materials- Physical Properties- (1992-)