THE EFFECTS OF BASE DOPANT DIFFUSION ON DC AND RF CHARACTERISTICS OF INGAAS/INALAS HETEROJUNCTION BIPOLAR-TRANSISTORS

The effects of base p-dopant diffusion at junction interfaces of InGaAs/InAlAs HBT's with thin base thicknesses and high base dopings are reported. It is shown that HBT's with compositionally graded emitter-base (E-B) junctions are very tolerant to base dopant outdiffusion into the E-B graded region. The RF performance is nearly unaffected by the diffusion and the dc current gain and E-B junction breakdown voltage are improved with finite Be diffusion into the E-B graded region.