A HIGH-CURRENT-GAIN, HIGH-SPEED P-N-P ALGAAS INGAAS/GAAS COLLECTOR-UPHETEROJUNCTION BIPOLAR-TRANSISTOR/

A P-n-p AlGaAs/InGaAs/GaAs collector-up heterojunction bipolar transis tor (C-up HBT), grown by three-stage molecular beam epitaxy, has been fabricated, and its dc and high-frequency performances have been evalu ated. The use of a graded InxGa1-xAs (x=0.0-0.09) is shown to improve the common-emitter current gain (beta) and to greatly reduce the base transit time (tau(b)) for the P-n-p C-up HBTs. A maximum current gain (beta) of 150 was measured for a 16X17 mu m(2) device. From S-paramete r measurements, a best unity-gain cutoff frequency f(T)=43 GHz at a co llector current of -10 mA was achieved using a 5X10 mu m(2) collector area. The results show that the P-n-p C-up HBTs may be useful for futu re planar integrated circuit applications. (C) 1995 American Institute of Physics.