Reliability analysis of microwave GaAs/AlGaAs HBTs with beryllium and carbon doped base

The reliability characteristics of microwave GaAs/AlGaAs negative-positive-negative (NPN) heterojunction bipolar transistors (HBTs) with beryllium (Be) and carbon (C) doped base layer have been investigated and compared by means of constant stress lifetest. Three groups of Be-doped devices using a newly developed molecular beam epitaxy (MBE) profile exhibited a median-time-to-failure (MTTF) of up to 1.8*10/sup 8/ hours at 125 degrees C junction temperature based on the lifetest characteristics of DC current gain, beta . The C-doped devices displayed a MTTF of 4.2*10/sup 5/ h under the same conditions. An equivalent failure rate of <0.1 FITs and 119 FITs at 10/sup 5/ h were calculated for Be and C doped devices, respectively.<
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