HIGH-QUALITY INTERFACES IN GAAS-ALAS QUANTUM-WELLS DETERMINED FROM HIGH-RESOLUTION PHOTOLUMINESCENCE

High resolution photoluminescence (PL) measurements performed on sever al GaAs-AlAs quantum well structures revealed sharp excitonic transiti ons separated in energies corresponding to roughly half-monolayer fluc tuations in well size. The narrow linewidths correlate with interface island structure whose lateral extent is either much larger or much sm aller than the exciton diameter. The half-monolayer separation results from a sharply peaked PL intensity response occurring around those ar eas of the laterally nonuniform interface which have roughly 50% islan d coverage, with the average island size much smaller than the exciton diameter, about 225 Angstrom. (C) 1997 American Vacuum Society. [S073 4-211X(97)04505-8].