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

Conference · Sun Nov 01 00:00:00 EST 1992

OSTI ID:6990863

Chambers, S A

Recent developments in the use of interlayers to tailor the Schottky barrier height (SBH) at a metal/GaAs interface are discussed. The goal has been to gain control of band bending in the interfacial region by modifying both the interface Fermi energy and the charge density in the depletion region. The approach has been to grow both the interlayer and the metal overlayer under ultrahigh vacuum conditions by molecular beam epitaxy, and then to determine the chemistry of interface formation, structure, and band bending by x-ray photoelectron spectroscopy and diffraction and by low-energy electron diffraction. The interface Fermi energy can be changed from the usual midgap value of 0.7--0.8 eV relative to the band edge by the use of epitaxial transition metal aluminide (TMA) overlayers such as NiAl. The unique chemistry of interface formation between this intermetallic compound and GaAs pins the Fermi level [approximately]0.3--0.4 eV above the valence band maximum, and results in a SBH of [approximately]1 eV. The SBH can be increased to [approximately]1.2 eV by the use of a wide bandgap interlayer such as AlAs. The charge density in the depletion region can be changed by growing an n[sup +]-type group IV interlayer between the TMA overlayer and GaAs substrate. Charge transfer from the interlayer to an n-type substrate reduces the space charge density, and thereby lowers the band bending and, thus, the SBH to [approximately]0.5 eV. The use of these interlayers then produces a range of SBH values of [approximately]0.7 eV, which is a significant improvement over the rather narrow range of 0.1--0.2 eV that results from conventional metallizations. The fundamental interface science that underpins these results is discussed, and an application to complementary digital GaAs circuit design that may significantly reduce gate leakage is given.

• Research Organization: Pacific Northwest Lab., Richland, WA (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6990863
• Report Number(s): PNL-SA-21356; CONF-921129-5; ON: DE93005029
• Resource Relation: Conference: 39. national symposium of the American Vacuum Society, Chicago, IL (United States), 9-13 Nov 1992
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
SEMICONDUCTOR JUNCTIONS
FERMI LEVEL
ALUMINIUM ALLOYS
BAND THEORY
CHARGE DENSITY
GALLIUM ARSENIDES
INTERFACES
INTERMETALLIC COMPOUNDS
NICKEL ALLOYS
ULTRAHIGH VACUUM
ALLOYS
ARSENIC COMPOUNDS
ARSENIDES
ENERGY LEVELS
GALLIUM COMPOUNDS
JUNCTIONS
PNICTIDES
665000* - Physics of Condensed Matter- (1992-)
360606 - Other Materials- Physical Properties- (1992-)
360104 - Metals & Alloys- Physical Properties