Influence of Holes Capture Efficiency on Photoluminescence Temperature Dependence of n -AlGaAs/GaAs Quantum-Well Structures

The process of excess current carriers capture from wide-gap barrier layers into a quantum well plays a decisive role in the operation of devices based on semiconductor structures. Among these devices are lasers, light-emitting diodes, and photodetectors. The oscillating dependence of the capture rate on the quantum-well width is poorly experimentally studied. The purpose of this study is to clarify the influence of oscillations of holes capture efficiency on the temperature behavior of photoluminescence in modulation-doped n-AlGaAs/GaAs heterostructures. Temperature measurements of the integrated photoluminescence intensity of structures with different quantum-well widths corresponding to different capture rates of holes (under conditions of resonant and nonresonant capture) are carried out. It is shown that the efficiency of hole capture influences not only the integrated photoluminescence intensity, but its temperature dependence as well. In resonant structures at low temperatures (77–140 K), the photoluminescence intensity decreases with increasing temperature more sharply than that in structures with inefficient capture. Such a difference is attributed to the fact that, under resonance conditions, the capture rate of holes is so high that its change with temperature does not influence the photoluminescence intensity, and the temperature quenching of photoluminescence is defined only by a decrease in the efficiency of radiative recombination β in the quantum well. In nonresonant structures, the temperature behavior of photoluminescence depends not only on the quantum efficiency β, but also on the local hole capture rate which increases, as temperature is elevated. The results of this study are of interest for optimizing the parameters of heterostructures in designing of devices, for which the efficiency of the capture of nonequilibrium charge carriers into a quantum well plays a decisive role.