Excess gate-leakage current of InGaAs junction field-effect transistors

Abstract

The excess gate-leakage current of InGaAs junction field-effect transistors (JFET), which is about 106 times that of the Si JFET, is attributed to hole-electron-pair generation produced by impact ionization of the high electric field in the JFET channel. The impact-ionization rate α is estimated from the excess gate-leakage current of the InGaAs JFET. At 77 K, the impact-ionization rate is about one-half compared with that of 300 K, and the difference between these two temperatures agrees with the calculated polar optical-phonon scattering rate. The excess gate-leakage current can be reduced by a factor of 7 by the introduction of a thin n-InP layer at the interface between the InGaAs channel and semi-insulating InP substrate.