A study of interface states in metal-GaAs 〈110〉 structures by Schottky capacitance spectroscopy

Abstract

A study of the capacitance of a forward biased Schottky diode as a function of bias, temperature, and frequency allows characterization of interface states at the metal-semiconductor junction. This method, called Schottky Capacitance Spectroscopy is applied to interfaces obtained by evaporating Au, Ag, or Al onto n-type cleaved GaAs 〈110〉 surfaces. We have explored the region of the semiconductor band gap about 1 eV below the conduction band minimum. There is evidence of three kinds of states. The energy levels of these states are quite reproducible while we have obtained a light dispersion of density of states and capture cross sections. Moreover, we have observed a correlation between the relative density of states C and the degradation of the I–V characteristic.