INGAAS RESONANT-TUNNELING TRANSISTORS USING A COUPLED-QUANTUM-WELL BASE WITH STRAINED ALAS TUNNEL BARRIERS

A bipolar-type resonant tunneling transistor is studied of which the base is identical to a coupled quantum well. On the basis of the InGaAs material system strained AlAs tunnel barriers and a graded InGaAlAs emitter are used. Molecular beam epitaxy growth conditions are studied, showing a specific influence of growth temperature and arsenic pressure. We find clear evidence for resonant tunneling: a saturation of the collector current and a maximum of the transconductance with increasing base-emitter bias in a three-terminal transistor structure. A corresponding effect in a phototransistor structure is found as a maximum of differential current gain with increasing incident light intensity. Room temperature and low temperature (80K) high-frequency properties are determined and are used to estimate the resonant tunneling time.