Pnp HBT with 66 GHz fmax

The total emitter to collector delay for a Pnp AlGaAs/GaAs HBT has been reduced to 4.8 ps by employing a thin base (325 /spl Aring/) and collector (2300 /spl Aring/). Simultaneously, a low base sheet resistance of 170 ohms/square was achieved with tellurium doping. A higher collector doping than is typically used permitted operation at collector current densities in excess of 5×10
⁴
A/cm
²
. A single emitter (2×4 μm
²
) and a single base contact device topology has an f
_T
and f
_max
of 33 and 66 GHz, respectively.