Direct variation of metal-GaAs Schottky barrier height by the influence of interface S, Se, and Te

Abstract

The electrical properties and interface chemistry of Schottky barrier contacts (Ag, Al, Au, Mn, Pd, and Ti) formed on n-type GaAs (100) surfaces that had prior exposure to elemental S, Se, and Te are compared to those of ideal (metal deposited onto a clean surface) contacts. The interface Fermi energy EiF and interface chemistry during contact formation were investigated by x-ray photoemission spectroscopy; the accompanying Schottky barrier height φB was measured by current-voltage and capacitance-voltage techniques. A substantial decrease in φB (and correlated change in EiF ) for Al and Mn contacts is associated with a contact metal-chalcogen chemical reaction at the Schottky barrier interface, while some nonreactive noble metal-chalcogen interfaces have a φB increase. By choice of contact metal and interface chalcogen a φB range of >0.6 eV is obtained (∼0.35 to 1.0 eV, which is >40% of the GaAs band gap) via corresponding changes in EiF.