OPTICAL STUDY OF HETEROINTERFACE CONFIGURATION IN NARROW GAAS ALGAAS SINGLE QUANTUM-WELLS PREPARED WITH GROWTH INTERRUPTION/

Photoluminescence and time-resolved photoluminescence were used to stu dy the heterointerface configuration in GaAs/AlGaAs quantum wells grow n by molecular-beam epitaxy with growth interruption. Photoluminescenc e spectra of the growth-interrupted sample are characterized by multip let structures, with energy separation corresponding to a 0.8 monolaye r difference in well width, rather than 1 monolayer as expected from t he ''atomically smooth island'' picture. By analyzing the thermal tran sfer process of the photogenerated carriers and luminescence decay pro cess, we further exploit the exciton localization at the interface mic roroughness superimposed on the extended growth islands. The lateral s ize of the microroughness in our sample was estimated to be 5 nm, less than the exciton diameter of 15 nm. Our results strongly support the bimodal roughness model proposed by Warwick et al. [Appl. Phys. Lett. 56, 2666 (1990)]. (C) 1996 American Institute of Physics.