Photoluminescence of self-assembled CdSe quantum dots by molecular beam epitaxy

Self-assembled CdSe single- and multi-quantum-dots layer structures were grown by molecular beam epitaxy with ZnSe barrier layer and were evaluated by photoluminescence measurements. The peak wavelengths of the emission spectra were around 480 nm for 1.7-2.3 monolayer (ML) supply and around 530nm for 2.6-4.0 ML supply in the single-quantum-dots layer samples. The optimum supplied amount of CdSe for the quantum-dots formation was determined to be around 2.6 ML. The integrated emission intensities increased on increasing the ZnSe barrier-layer thickness in the muiti-quantum-dots layer samples with the same total barrier-layer thicknesses. The integrated emission intensities of the multi-quantum-dots layer structures with constant barrier-layer thickness proportionally increased on increasing the total barrier-layer thickness and were saturated above the total thickness of about 2200 Angstrom, which corresponds to the thickness dependence of the number of photo-generated carriers that are provided to the quantum dots. (C) 2001 Elsevier Science B,V. All rights reserved.