Effects of InGaP heteropassivation on reliability of GaAs HBTs

For the self-aligned AIGaAs/GaAs HBTs with the mesa-etched emitter, the instability of the surface states on the extrinsic base passivated by nitride is a major cause of the severe degradation of current gain. In this paper GaAs HBTs employing inGaP ledge emitter in order to passivate the surface of the extrinsic base and to reduce the surface states exhibited the considerable improvement of the current gain reliability with the activation energy of 1.97 eV and MTTF of 4.8 x 10^8 h at 140°C. However, under the strong stress conditions InGaP/GaAs HBTs also produced the considerable degradation. The possible origins were investigated. © 1999 Elsevier Science Ltd. All rights reserved.