Thermally-enhanced current gain of quantum-well heterojunction bipolar transistor

Abstract

We investigate the current gain of quantum-well heterojunction bipolar transistors (QW-HBTs) under different operation temperatures. It is experimentally shown that the introduction of a QW into the base region of HBTs results in an increasing current gain with the temperature, which is a behavior opposite to that of typical HBTs. An enhancement of current gain around 226% is observed as the temperature of QW-HBT is raised from 35 to 95 degrees C. This unusual trend is mainly attributed to the shorter escape time of electrons in the QW at the higher temperature. A modified charge-control model based on thermionic emissions of electrons in the QW region is constructed to model this temperature-dependent phenomenon, and the result agrees well with our experimental observations.