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.