Low-temperature characterization of high-current-gain AlGaAs/GaAs narrow-base heterojunction bipolar transistor

摘要

Abstract: AlGaAs/GaAs Narrow Base Heterojunction Bipolar Transistors (NBHBTs) with 50 angstroms thick bases exhibit maximum small signal common emitter current gains h$-fe$/ of 1400 at 300 K and 3000 at 80 K. The performance of the device is attributed to the superlattice graded emitter contact and a novel planar base access fabrication process. Low temperature measurements indicate that the maximum current gain increases exponentially with decreasing temperature until is saturates around 200 K, suggesting a tunnelling limited current transport mechanism.!23