ROOM-TEMPERATURE INGAAS COUPLED-QUANTUM-WELL BASE TRANSISTOR WITH A GRADED EMITTER

We describe a resonant tunneling transistor with a coupled-quantum-well base operating at room temperature. The molecular beam epitaxy grown InGaAs material system is used. Three thin planar-doped quantum wells separated by strained AlAs barriers constitute the transistor base. A parabolically graded InGaAlAs emitter layer suppresses hole injection into the emitter and enhances the current gain. The DC characteristics show a clear saturation of the collector current with increasing base current, which is evidence for resonant tunneling. Cutoff frequencies are determined employing S-parameter measurements, and the resonant tunneling transit time is estimated.