Control of GaAs Schottky barrier height by formation of a thin off-stoichiometric GaAs interlayer grown by low-temperature molecular beam epitaxy

Abstract

Thin (10 to 20-Å-thick) nonstoichiometric GaAs layers were grown by molecular beam epitaxy at 200 °C under a wide range of As pressure and placed at the interface of metal-GaAs Schottky barriers. The influence of these interlayers on the Schottky barrier heights was explored. By changing the As pressure for the interface film growth, the Schottky barrier heights obtained using both Al and Au metals varied in the range of 0.5 to 1.0 eV on n-GaAs and of 0.4 to 0.9 eV on p-GaAs. The wide variation of barrier heights, essentially independent of metal work function, can be explained by a strong Fermi-level pinning controlled by the defect levels in the interface layer. These defects are directly related to the layer’s nonstoichiometry.