Effect of semiconductor growth method and bulk doping on fermi level stabilization for aluminum and gold contacts on n- and p-GaAs(100)

Abstract

Effects of substrate doping and growth method on interface deep level formation and Schottky barrier height were investigated using low-energy catho doluminescence and soft x-ray photoemission spectroscopy. Our results reveal that for Au/GaAs(100) contacts Fermi level (EF) stabilization energy shows little sensitivity to either substrate growth technique or the type of doping, and Iles in the 0.37 to 0.47 eV range above the valence band maximum (Ev). In contrast, the EF position at Al/GaAs(100) interfaces is highly sensitive to substrate growth method for n-type GaAs, but shows no significant difference between the epitaxial and melt-grown p-type GaAs. Furthermore, for a specific substrate dopant type and growth method, gold and aluminum produce barrier heights which differ by 0.05 to 0.50 eV, depending upon the substrate growth and dopant properties. Cathodoluminescence results demonstrate that discrete surface and interface states responsible for EF stabilization at these metal/GaAs junctions are highly sensitive to the substrate growth technique, as well as to the specific metal contact. This work emphasizes that both substrate crystalline and electronic properties, as well as the adatom-specific interface chemistry are crucial for the electrostatic barrier height formation at metal/GaAs contacts. © 1993 The Mineral,Metal & Materials Society,Inc.