Determination of InP-based HBT device models at end of life

Abstract

InP-based HBTs have been stressed to approximate degradation from a 15 year system life and device models were generated. The basic characteristics of these models are increases in the emitter resistance (Re) and in the base-collector capacitance (Cjc). The end of life model can be obtained from the standard model by increasing Re from 3.6 to 5.7 /spl Omega/ and Cjc from 20.1 to 23.4 fF. These changes lead to decreases in: transistor gain, Ft, and Fmax, and an increase in the base-emitter voltage (V/sub bel/) at typical operating conditions. The changes in the device parameters generally fall within the normal process variations. No increase in low current base emitter voltage (V/sub be0/) occurs, indicating the lack of Be diffusion into the emitter.