Investigation of the temperature dependent recombination processes in periodic four-narrow-asymmetric-coupled-quantum-well structures

Continuous-wave intensity-dependent photoluminescence spectra of periodic four-narrow-asymmetric-coupled-quantum-well structures were measured at different temperatures. Above 215 K, the photoluminescence depends linearly on high pump laser intensities and quadratically on low pump laser intensities. This is due to the competition between radiative recombination, and nonradiative recombination of carriers at excitation intensity saturable deep traps. Below 215 K the trapping becomes negligible and the photoluminescence is linearly proportional to all laser intensity levels; radiative recombination dominates. Based on this transitional (from quadratic to linear) behavior of the photoluminescence and our simple theory, the transition intensity, the effective nonradiative decay time of the carriers, and the photoluminescence quantum efficiency have been determined as a function of temperature.