We have undertaken a detailed experimental study of the electric-field-dependent coupling between two identical GaAs quantum wells separated by a narrow AlGaAs barrier using photoluminescence (PL), transient PL, and PL excitation spectroscopy. It was found that the coupling of the wave functions in a coupled double-quantum well (CDQW) structure produces a splitting of the single-well levels. The influence of an electric field on the exciton states in such a structure showed clear evidence that both intrawell and interwell exciton transitions occur. Furthermore, the effect of rapid thermal annealing (RTA) on these CDQW structures with and without SiO2 cap layers was also studied. While RTA without a capping layer produced only minor changes in the PL spectrum, the combination of a 300 nm SiO2 overlayer plus RTA caused a shift to lower energy of the main PL peak. This difference was attributed to a change in the shape of the CDQW structure caused by capped RTA.
