High quality interfaces in GaAs–AlAs quantum wells determined from high resolution photoluminescence

Abstract

High resolution photoluminescence ͑PL͒ measurements performed on several GaAs-AlAs quantum well structures revealed sharp excitonic transitions separated in energies corresponding to roughly half-monolayer fluctuations in well size. The narrow linewidths correlate with interface island structure whose lateral extent is either much larger or much smaller than the exciton diameter. The half-monolayer separation results from a sharply peaked PL intensity response occurring around those areas of the laterally nonuniform interface which have roughly 50% island coverage, with the average island size much smaller than the exciton diameter, about 225 Å.