High performance of IR detectors due to controllable kinetics in quantum-dot structures

Abstract

ABSTRACT To optimize the photodetector based on quantum-dot (QD) structures, we develop and exploit a model of the room-temperature QD photodetector. Using analytical modeling and Monte-Carlo simulations, we investigate photoelectron kinetics, i.e. capture and transit processes, as functions of selective doping of a QD structure, its geometry, and electric field applied. Results of our simulations demonstrate that the photoelectron capture is substantially enhanced in strong electric fields. Detailed analysis shows that effects of the el ectric field on electron capture in the structures with barriers are not sensitive to the redistribution of electrons between valleys. Thus, most data find adequate explanation in the model of hot-electron transport in the potential relief of quantum dots. We also show that the photoelectron kinetics is very sensitive to potential barriers of intentionally or unintentionally charged quantum dots. The capture processes can be substantially suppressed by a proper choice of the geometry of a QD structure and modulation doping. The suggested model is in agreement with the available experimental results. Manageable kinetics will allow one to employ QDIP as an adaptive detector with changing parameters. Keywords: infrared photodetector, quan tum-dot structure, potential barriers, photoelectron capture.