Reliability of InGaAs/InP HBTs with InP passivation structure

We have fabricated InGaAs/InP HBTs with an InP passivation structure and characterized reliability. Life tests of the HBTs under a collector current density of 100 kA/cm/sup 2/ were carried out at junction temperatures of 255/spl deg/C and 280/spl deg/C. The HBTs have shown a low emitter-base current and stable characteristics in the life tests compared with HBTs without the InP passivation structure. The variations of current gain and turn-on voltage at a collector current density of 100 kA/cm/sup 2/ are within -7% and -1%, respectively, after 4,411 hours in the life test of 255/spl deg/C. We have obtained the activation energy of 1.5 eV and the mean time to failure of 5 /spl times/ 10/sup 6/ hours at a junction temperature of 150/spl deg/C, which is sufficient for practical applications.