Study of Failure Mechanisms in InP/GaAsSb/InP DHBT Under Bias and Thermal Stress

This paper presents results of aging tests performed on InP/GaAsSb/InP HBTs leading to the identification of a typical failure mechanism. Submitted to combined thermal and current stresses, HBTs under test present a current gain degradation. The modeling of the current gain degradation with stress time allows to evaluate a time to failure and reveal its thermal dependence through the extraction of an activation energy of 0.94plusmn0.03 eV. Discussion on the physical origin of the failure mechanism concludes on (i) the possible localization of the failure mechanism near the surface of the device at the semi-conductor-passivation interface and (ii) the possible presence of pre-existing defects triggered to become electrically active by the stress conditions.