Reliability characteristics of GaAs and InP-based heterojunction bipolar transistors

The reliability characteristics of Heterojunction Bipolar Transistor made on GaAs and InP substrates are reviewed and ways of improving them by design, growth and processing are described. Materials for HBTs are grown by a variety of techniques (MBE. MOCVD, CBE). Their choice is made based on considerations such as satisfaction of design requirements and manufacturing but also dopant incorporation without risk of diffusion, as well as, minimization of hydrogen incorporation which may result in device degradation. The minority carrier lifetime in the base is influenced by hydrogen incorporation in C-InGaAs. Conventional alloyed and non-alloyed, as well as, refractory metallization schemes are considered for best reliability performance. The dielectric deposition scheme used for passivation plays a major role on device reliability. Good reliability performance is reported for GaAs but also for inP-based HBTs. A correlation is finally reported to exist between the low-frequency noise properties of HBTs and their reliability characteristics. (C) 1999 Elsevier Science Ltd. All rights reserved.