Formation and characterization of self-organized CdSe quantum dots

We have investigated the formation and characteristic of self-organized CdS e quantum dots (QDs) on ZnSe(001) surfaces with the use of photoluminescenc e (PL) and transmission electron microscopy (TEM). Coherent CdSe QDs are na turally formed on ZnSe surfaces, when the thickness of CdSe layers is aroun d 2 ML. The plan-view TEM images exhibit that CdSe QDs have a relatively na rrow distribution of QD size, and that the density of CdSe QDs is about 10( 10) cm(-2). The base structure of the CdSe dot is rhombic, which has the lo ng axis of about 20 nm in length along [1 (1) over bar 0] direction. The te mperature dependence of macro-PL spectra reveals that the behavior of self- organized CdSe QDs is quite different from that of ZnCdSe quantum well (QW) , resulting from characteristic features of zero-dimensional structures of QDs. Moreover, the macro-FL results suggest the existence of QW-like contin uous state lying over QD states. Micro-PL measurements show several numbers of high-resolved sharp lines from individual CdSe QDs. The linewidth broad ening with temperature depends on peak energy position of the QDs. The line widths of lower energy lines, corresponding to larger size QDs, are more te mperature dependent.