In Situ Monitoring And Control For MBE Growth Of Optoelectronic Devices

Self-organized CdSe/ZnSe quantum dots (QD's) were fabricated on the cleavage-induced GaAs (110) surface in ultra high vacuum (UHV) by molecular beam epitaxy (MBE). CdSe layer showed the Stranski-Krastanow (S-K) growth mode. QW's and QD's emissions originated from the wetting layer and island structures, respectively, were observed in photoluminescence (PL) spectra. This is a evidence of S-K type where island structures are self-formed on the two-dimensional wetting layer as a result of the transition of the growth mode. The state filling effect in the QD's was also observed by employing excitation power dependence on the PL intensity. By using the microscopic PL spectroscopy, the broad PL peak of QD's was resolved into a number of sharp peaks. These peaks are attributed to the recombination of excitons localized at the individual QD's indicating that the fabricated CdSe islands have quasi-zero-dimensional δ-function like density of states.