On the recombination currents effect of heterostructure-emitter bipolar transistors (HEBT's)

In this paper, we will demonstrate the effect of recombination current on the electrical properties of heterostructure-emitter bipolar transistors (HEBT's), For comparison, an AlGaAs/GaAs and an AlInAs/GaInAs BEET are fabricated with the layer structure, For the AlGaAs/GaAs HEBT, the hole diffusion length is larger than the emitter thickness, so that most of holes can be reflected back at the confinement layer due to the hole recombination current is low in the neutral-emitter region, Thus, the high emitter injection efficiency and current gain can be achieved simultaneously, On the other hand, for the AlInAs/GaInAs HEBT, the increase of recombination current at neutral emitter regime rand the existence of potential spike could reduce the emitter injection efficiency at large V-BE voltage, Hence, the non-1KT component of collector current is enhanced and the characteristics of transistor are degraded, However, a lower offset voltage of 40 mV is obtained attributed to the low base surface recombination current for the AlInAs/GaInAs HEBT.