Compensation of Charge Fluctuations in Quantum Wells with Dual Tunneling and Photon-Assisted Escape Paths

摘要

In their previous article D. H. Huang, A. Singh, and D. A. Cardimona, Journal of Applied Physics, v87, 2427 (2000), the authors explained the experimentally observed zero-bias residual tunneling current A. Singh and D. A. Cardimona, Opt. Eng., v38, 1424 (1999) in quantum-well photodetectors biased by an ac voltage. In this article, they extend their theory to include the photoemission current and to reproduce their recent finding on the dynamical drop of photoresponsivity from its static value in quantum-well photodetectors as a function of the chopping frequency of the incident optical flux. In this theory, they derive a dynamical equation for a nonadiabatic space-charge field in the presence of an applied electric field and an incident optical flux. From it, a compensation of the charge fluctuations in quantum wells is predicted as a result of dual tunneling and photon-assisted escaping paths. They also find a suppression of the nonadiabatic deviation of photoresponsivity from its static value due to a charge-depletion effect in quantum wells.