Analysis of GaAs HBT failure mechanisms: impact on life test strategy

A field-induced degradation mechanism responsible for the surface current drift in GaAs HBT is identified on the basis of accelerated ageing tests under bias. Degradations of ohmic contact and metallisation are highlighted under high temperature storage. These results bring further evidence of both bias and temperature-induced degradation mechanisms in GaAs HBTs. As a consequence, a specific life test strategy similar to that implemented for FETs has been derived.