Space-charge recombination currents and their influence on the dc current gain of AlGaAs/GaAs Pnp heterojunction bipolar transistors

The effects of Shockley-Read-Hall, Auger, radiative, and intrinsic surface base recombination processes in the emitter-base space-charge region on the current gain of Pnp AlGaAs/GaAs heterojunction bipolar transistors are analyzed. At low forward emitter-base bias, the current gain of a typical Pnp AlGaAs/GaAs heterojunction bipolar transistor is shown to be reduced substantially below its value calculated while neglecting recombination currents in the emitter-base space-charge region. Excellent agreement between theory and experiment is found for the current gain variation versus collector current density for a Pnp device recently reported by Slater [IEEE Electron Device Lett. 15, 91 (1994)]. (C) 1999 American Institute of Physics. [S0021-8979(99)03324-1].