High-speed InGaP/GaAs heterojunction bipolar transistors with buried SiO2 using WSi as the base electrode

High-speed InGaP/GaAs heterojunction bipolar transistors (HBT's) with a small emitter area are described. WSi is used as the base electrode to fabricate HBT's with a narrow base contact width and a buried SiO
₂
structure. An HBT with an emitter area of 0.8×5 μm exhibited an f
_T
of 105 GHz and an f
_max
of 120 GHz. These high values are obtained due to the reduction of C/sub BC/ by using buried SiO
₂
with a narrow base contact width, indicating the great potential of GaAs HBT's for high-speed and low-power circuit applications.