Model for degradation of GaAs/AlGaAs HBTs under temperature and current stress

Abstract

The similarities between GaAs/AlGaAs heterojunction bipolar transistors (HBTs) and GaAs-based light-emitting diodes (LEDs) and laser diodes (LDs) under current and temperature stress are demonstrated. Electroluminescence on HBTs with degraded current gain shows a marked decrease in light emission. One device which suffered rapid degradation in current gain also showed a <110> dark line defect (DLD). Finally, an equation used to model light output as a function of time under bias stress in LEDs and LDs was modified to model collector current vs. time for HBTs under bias stress. An excellent fit to the data is shown.

GaAs HBT Reliability

“…It is easy to find favorable reliability reports where the initial transient drift or middle gradual drift region has been analyzed for MTTF and Ea, but such analyses say nothing about the fundamental sudden β failure mode. Sudden β failures are thought to arise in much the same ways as GaAs LEDs fail [4,11]. A defect is present or forms, then grows rapidly, possibly feeding off of > 1eV photon energy.…”

A statistical approach to characterizing the reliability of systems utilizing HBT devices

“…HBT device reliability has been extensively studied and HBT device life has been demonstrated to follow the following equation [1][2][3] ttf ¼ CJ Àa e Ea=kT j ð1Þ…”

Very High Speed SiGe Heterojunction Bipolar Transistor Reliability Overview

“…This difference in thermal response manifests itself in the wellknown device failure mechanisms of Ill-V systems [8] [9][I10], and the observation that such failure mechanisms have not been reported in silicon or SiGe systems. Common failure mechanisms in Ill-V are movement of dopants or host atoms.…”