Formation and characteristics of wide band gap II-VI semiconductor quantum dots

CdSe and ZnCdSe quantum dots (QDs) were grown under Stranski-Krastanow (S-K) mode by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The formation process of CdSe QDs below critical thickness was observed by atomic force microscopy (AFM). The formation mechanism of CdSe QDs below the critical thickness was due to the effect of surface diffusion and strain release. ZnCdSe QDs were grown based on the calculated critical thickness. Two kinds of variations in the ZnCdSe QDs appeared over time, the Ostwald ripening process and dot formation process. ZnSeS dots were grown under Volmer-Weber (V-W) mode. With increasing the growth duration, the size of dots becomes larger and the density decreases, which is explained by virtue of the surface free energy.