Reliability study of InP-based HBTs operating at high current density

Abstract

The high-speed and low-power operation of InP-based heterojunction bipolar transistors (HBTs) makes them very attractive for use in opticalcommunication ICs operating at 40 Gbit/s and more. An important requirement for InP HBTs is long-term stability in their electrical characteristics under high current-density operation. This chapter describes the degradation behavior for devices operating at current densities of up to 10 mA/μm2 under elevated ambient temperatures. The results of electrical measurements and microscopic analyses indicate that surface passivation in the external base, a refractory electrode on the emitter, and high crystal quality at the emitter-base junction are the keys to enhancing device reliability.