Transient effects in InAs/GaAs quantum-dot detectors under low-temperature and low-background conditions

Abstract

In the presence of a time-dependent external source such as a bias electric field or an incident optical flux, electrons in quantum well and quantum dot devices experience non-adiabatic transport through the barrier layer between two adjacent quantum wells or quantum dots. This non-adiabatic transport process induces charge density fluctuations, resulting in several transient phenomena. When a time-dependent electric field is applied to the system, a dynamical breakdown (i.e., the dark current is dominated by a dielectric displacement current) of the quantum well or quantum dot photodetector is observed. If a chopped time-dependent optical flux is incident on either system, a dynamical drop in the photo-responsivity with increasing chopping frequency is also observed.