Reliability and failure criteria for AlInAs/GaInAs/InP HBTs

We have performed accelerated temperature and bias lifetests on single-heterojunction AlInAs/GaInAs/InP bipolar transistors (HBTs). Discrete HBTs were fabricated and stressed at bias conditions of high collector-emitter voltage, typical operating current (V/sub CE/=3 V and J/sub C/=23 kA/cm/sup 2/), and at junction temperatures (T/sub j/) of 205/spl deg/C and 225/spl deg/C. Previous lifetests had been presented at higher junction temperatures (T/sub j/>230/spl deg/C) and up to 2000 hours of stress. In this work, we report results from stress tests up to 6000 hours. Failure criteria defined by base-emitter turn-on voltage (V/sub BE/) and dc-gain (/spl beta/) degradation demonstrate a robust technology with activation energies (E/sub a/) greater than 1.1 eV and extracted median-time-to-failure (MTTF) in excess of 10/sup 7/ hours at T/sub j/=100/spl deg/C.