HIGH-PERFORMANCE LOW-BASE-COLLECTOR CAPACITANCE ALGAAS/GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS FABRICATED BY DEEP ION-IMPLANTATION

Low-base-collector capacitance (C-bc) AlGaAs/GaAs HBT's with f(MAX) > 200 GHz and f(T) = 52 GHz have been fabricated, With co-implants of high energy, high dose He+ and H+ ions through the external base layer, part of the heavily doped n(+) sub-collector was compensated leading to a decrease in the extrinsic portion of C-bc. The implants caused only a slight increase of base resistance, Using this approach in combination with a standard low dose, shallow collector compensating implant, C-bc of double implanted HBT's can be reduced by more than 35%.