抄録
GaAs/AlGaAs hetero-junction bipolar transistors (HBTs) have attracted much attention because of their high-speed performance. However, long-term operation seriously degrades the device characteristics: Current gain decreases and low-bias-leakage current increases. This degradation has long been an issue in GaAs-based devices operated under minority-carrier injection, like laser diodes. The cause of degradation is thought to be in the carbon-doped base, but this is not yet certain. In this paper degradation of HBTs is described, especially GaAs/AlGaAs HBTs with heavily carbon-doped base layer. Here, two types of the device degradation are found, i.e., hydrogen-related degradation and carbon-related degradation. The mechanisms governing the degradation are discussed from the framework of recombination enhanced defect reaction (REDR) and charge state effect (CSE).
