An analysis of small-signal response of the SiO2-(n) GaAs interface based on a surface disorder model

An attempt to clarify the frequency behaviour of the (n) GaAs-SiO2 interfac e has been presented. Metal-SiO2-GaAs structures with a PECVD-deposited ins ulator layer have been investigated. The measurements of capacitance-voltag e characteristics at different frequencies as well as the frequency depende nce of MIS capacitance and conductance at fixed gate voltages have been per formed. A large frequency dispersion of MIS admittance has been revealed. T he model of an insulator-semiconductor interface as a disordered system wit h localized electron states distributed in energy and in space can be used to explain the experimentally observed broad spectrum of time constants. Th e method of analysis of measured characteristics is based on a least-square s fitting of experimental data with theoretical dependencies allowed to det ermine the parameters of the interface states as well as some parameters of MIS structures. (C) 1999 Elsevier Science Ltd. All rights reserved.