Characterization of recombination processes in multiple narrow asymmetric coupled quantum wells based on the dependence of photoluminescence on laser intensity

Abstract

Continuous-wave intensity-dependent photoluminescence spectra of multiple narrow asymmetric coupled quantum wells at room temperature have been measured. At low laser intensity, the total photoluminescence intensity is primarily proportional to the square of the laser intensity due to dominant nonradiative recombination of free carriers at nearly saturated interface traps. At high laser intensity, however, the total photoluminescence intensity approaches a level proportional to the laser intensity due to radiative recombination of free carriers. Based on this transition behavior, which has been observed for the first time to the best of our knowledge, and our simple theory, the transition intensity, the nonradiative decay time of the carriers, and the intensity-dependent carrier density and photoluminescence quantum efficiency have been determined.