Optical characterization of ZnSe/ZnMgSSe microdisks with embedded CdSe quantum dots

We report on photoluminescence (PL) studies of ZnSe/ZnMgSSe microdisks with embedded CdSe quantum dots. The multilayer structure was grown by molecular beam epitaxy with a single layer of self-assembled quantum dots. Microdisks were realized by electron beam lithography and etching techniques. To avoid absorption losses, the GaAs substrate was removed totally. Optical confinement is demonstrated by the appearance of whispering gallery modes. Lasing of quantum dots with low thresholds and β factors close to unity were observed, reflecting an excellent coupling of the microdisk modes with the quantum dots. At room temperature, optical modes with quality factors of several thousands dominate in the quantum dot spectrum in the green spectral range. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)