Silicon etched-groove permeable base transistor fabrication with cutoff frequencies (fT, fmax) above 25 GHz

We report the fabrication of etched-groove silicon permeable base transistors (PBTs) with mushroom-shaped 0.2-0.4 μm wide source fingers. This structure enables both the passivation of the Si finger sidewalls and the reinforcement of the platinum gate with a gold overlayer. The low base resistance and the optimized doping profile yielded devices with f
T
and f
max
values up to 26 GHz.