Electrical properties of the gallium arsenide–insulator interface

Abstract

Extensive capacitance–voltage (C–V) measurements have been performed on three types of insulators on n-type GaAs: pyrolytically deposited silicon nitride, sputtered silicon nitride, and the oxide produced by anodization. Evaporated aluminum gate contacts and alloyed Au–Ge ohmic contacts were applied and the C–V characteristics of these structures were measured from the quasistatic regime to 150 MHz. Although differences in detail are seen at intermediate frequencies, the data taken at the extreme frequency limits differ very little for the three types of specimens. The quasistatic and high-frequency data are consistent with a model wherein the surface potential with zero applied gate bias is ∠−0.8 V. Application of electric fields of the order of ±106 V/cm at the semiconductor surface results in movement of the surface potential across approximately 1/3 of the band gap. An accumulation layer of surface electrons could not be produced on any of the devices tested.