BIAS DEPENDENCE OF RESPONSIVITY AND TRANSPORT IN ASYMMETRIC QUANTUM-WELL INFRARED DETECTORS

A new type of asymmetric stepped GaAs/AlGaAs multiquantum well infrared detector is reported. These asymmetric detectors utilize the usual bound-to-continuum transition. The current responsivity is remarkably asymmetric with regard to the voltage polarity. In contrast with rectangular wells, in which responsivity is saturated in both bias polarities, these wells exhibit saturation only for negative bias. The responsivity increases monotonously with positive electric field. This is attributed to changes induced by the field on the transport properties of the excited electrons. In particular, the bias affects the dwell time spent by the carrier wave packet in the well region. Employing this model, we achieve a very good fit with experimental data.