COMPARISON OF GAINP GAAS HETEROSTRUCTURE-EMITTER BIPOLAR-TRANSISTORS AND HETEROJUNCTION BIPOLAR-TRANSISTORS/

Carbon-doped GaInP/GaAs heterojunction bipolar transistors (HBT's) and heterostructure-emitter bipolar transistors (HEBT's) grown by MOCVD w ere fabricated, Experimental comparison of HBT's and HEBT's has been m ade based on the de and the RF performance, HBT's have higher current gains than those of HEBT's in the high current regime, while HEBT's of fer a smaller offset voltage and better uniformity in de characteristi cs across the wafer, The current gain and cutoff frequency of the HEBT with a 150 Angstrom emitter set-back layer are comparable to those of HBT's, DC (differential) current gains of 600 (900) and 560 (900) wer e obtained at a collector current density of 2.5 x 10(4) A/cm(2) for t he HBT and DEBT, respectively, The cutoff frequencies are 37 and 31 GH z for the HBT and DEBT, respectively, It is shown that there is neglig ible contribution of the diffusion capacitance to the emitter capacita nce in HEBT's with a thin emitter set-back layer but not with a thick emitter set-back layer, The behavior of HEBT's both in de and RF chara cteristics is similar to that of HBT's.