Isothermal capacitance transient spectroscopy of pseudomorphic high-electron-mobility transistors

The surface electronic properties of AlGaAs/InGaAs pseudomorphic high-electron-mobility transistors were investigated by isothermal capacitance transient spectroscopy (ICTS) and gate-leakage current characteristic measurements. Both hole- and electron-like trap spectra were observed by ICTS measurements on gate–source/drain capacitance. We observed enhancement of leakage current and drastic change of static and transient capacitance behavior around a pinch-off voltage. The leakage characteristics and ICTS results were explained in terms of a surface states model.