Role of X valley on the dynamics of electron transport through a GaAs/AlAs double-barrier structure

Abstract

The transport of electrons through a GaAs/AlAs double-barrier structure with p-type doped contacts was investigated using time-resolved photoluminescence spectroscopy. Under illumination, the current-voltage characteristics of the device present two additional features attributed, respectively, to resonant Gamma-Gamma and Gamma-X electron tunneling. Optical measurements for biases where these two alternative transport mechanisms have competitive probabilities revealed an unusual carrier dynamics. The quantum well emission is strongly delayed and we observe a remarkable nonlinear effect where the emission intensity decreases at the arrival of a laser pulse. We propose a simple model that adequately describes our results where we assume that the indirect-transition rate depends on the density of electrons accumulated along the structure.