Jh. Son et al., ALGAAS GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS WITH REDUCED BASE-COLLECTOR CAPACITANCE FABRICATED USING SELECTIVE METALORGANIC CHEMICAL-VAPOR-DEPOSITION/, JPN J A P 1, 34(2B), 1995, pp. 1085-1088
Selectively grown AlGaAs/GaAs heterojunction bipolar transistor (HBT)
with a reduced base-collector capacitance is proposed and fabricated u
sing selective metalorganic chemical vapor deposition (MOCVD) techniqu
e. The proposed HBT features a triangular void over SiO2 stripe. The e
xtrinsic base-collector capacitance is significantly reduced due to th
e isolation of the extrinsic collector region from the collector metal
-contact by the void. The DC current-voltage characteristics of the se
lectively grown HBT are similar to those of the conventional one. Howe
ver, the microwave performance is improved due to the reduced base-col
lector capacitance in the selectively grown HBT. For the device with t
wo 3 x 10 mu m(2) emitter fingers, the selectively grown HBT has a max
imum oscillation frequency 1.4 times higher than that of the conventio
nal device, and the current gain cutoff frequency f(T) of 43 GHz and t
he maximum oscillation frequency f(max) of 20.5 GHz are obtained.