Operation of a ballistic heterojunction permeable base transistor

A ballistic heterojunction permeable base transistor (HPBT) is proposed and an analytical and numerical analysis of the device is performed. The new feature of the device structure is an AlGaAs hetero-emitter for injection of hot electrons into a 150-nm-thick GaAs base layer. A tungsten grating is embedded in the base layer and the Schottky depletion around the metal wires controls the vertical current. In this investigation, it is established that the high velocity of the hot electrons will prevent charge accumulation in the base layer. Thereby the dependence of the doping on the transconductance is lower than for the permeable base transistor. The HPBT is expected to have a unity-current gain cut-off frequency above 300 GHz.