Surface Field Effect Device Studies for High Resistivity Gallium Arsenide. Part I: Surface States on Gallium Arsenide

摘要

Surface states on a GaAs (110) surface were studied by capacitance measurements on an MIS (metal-insulatorsemicondutor) diode. In particular, the small signal high frequency differential capacitance of an Al-evaporated SiOGaAs diode as a function of d.c. bias is presented. This curve is then compared to the theoretical variation of the ideal MIS diode (without surface states) and the surface state density as a function of position in the bandgap is determined. Results indicate a distribution of states very similar to that determined by Terman (Sol. St. Elect., p. 285) and Lehovec (Phy. Stat. Sol., 3, p. 447) for the Al-thermally grown SiO2-Si system except for a factor of 10 less states on the GaAs. Contribution of charge due to ionization of bulk traps prohibited the extension of the MIS measurements, which were performed on 0.1 ohm centimeter material, to higher resistivities. (Author)