Tunneling emitter undoped quantum-well infrared photodetector

An extensive series of measurements and theoretical analysis are presented on an undoped single-quantum-well infrared photodetector. The well is filled by electron tunneling through the thin emitter barrier resulting in several novel characteristics compared with the usual directly well-doped detectors. These include a unity optical gain and a dramatic drop in the well carrier density (and responsivity) at high bias when the bound state in the well drops below the emitter conduction-band edge.