Surface states at the nGaAsSiO2 interface from conductance and capacitance measurements

Abstract Conductance and capacitance measurements have been used to investigate the interface properties of MOS capacitors formed by depositing an insulating layer of SiO 2 on n -type GaAs. The surface potential as a function of applied bias is evaluated using results of high and low frequency capacitance measurements and the two methods are found to yield roughly similar results. The interface state density evaluated from the conductance and capacitance measurements is found to peak near the center of the band gap and also near the conduction band edge. Plots of conductance vs frequency indicate the presence of both fast and slow interface states in these materials.