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

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.