Electrical properties of a heterojunction bipolar transistor structure with a resistive gate

Abstract

A conventional heterojunction bipolar transistor with a resistive gate, formed by placing the third location in the depletion region of the collector layer instead of the base layer, is investigated. The influences of the gate voltage on the device performance then strongly depend on the applied voltage. The results show that the device operated under voltage-controlled mode exhibits novel N-shaped negative differential resistance (NDR) characteristics, which have large room temperature NDR peak-to-valley current ratios (e.g. 140 at a gate bias of 1.5 V) and large voltage extension in N-shaped NDR region (about 9 V). However, the device exhibits the transistor characteristics with the current gain of 4 under current-injected mode. The above discrepancies between voltage-controlled and current-injected modes are attributed to the existence of the resistive gate.