J. Würfl, P. Kurpas, F. Brunner, M. Mai, M. Rudolph, M. Weyers

Published in:

Microelectron. Reliab., vol. 41, no. 8, pp. 1103-1108 (2001).

Abstract:

Reliability tests at different ambient temperatures and biasing conditions have been performed on GaInP/GaAs heterojunction bipolar transistors. The epitaxial layer structure of the transistors has been grown by MOVPE, device processing utilized a triple mesa approach to access the base and collector regions and to perform interdevice isolation. A GaInP ledge structure suppresses excessive surface recombination currents. Reliability tests demonstrated a characteristic degradation behaviour of the transistors. It consists of a burn-in phase at the beginning of lifetime, followed by a rather stable phase with only minor degradation and a rapid decay of performance at the end of lifetime. It could be shown that the course of degradation and burn-in with time strongly depends on the parameters of reliability testing. Furthermore there is an indication that reliability also depends on crystal growth technology of the GaAs substrates. A device lifetime (mean time to failure MTTF) of up to typically 3×10⁷ hours could be determined for a collector current density of 1×10⁵ A/cm² and a junction temperature of 125°C.

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