Formation mechanism and properties of CdSe quantum dots on ZnSe by low temperature epitaxy and in situ annealing

The formation mechanism of CdSe quantum dots (QDs) on ZnSe by low temperature epitaxial growth of a CdSe layer and its subsequent in situ annealing at a higher temperature has been studied. By this method, a small postgrowth residue of mobile adatoms nucleates distinct, stable, three-dimensional islands atop preexisting two-dimensional (2D) precursors. High temperature annealing activates an up-climb of these adatoms onto the 2D precursors, which, however, predominantly climb down at the low growth temperature (T_G). A growth interruption at T_G, therefore, smoothens the as-grown CdSe layer, and when introduced for appropriate durations, enables reducing the QD areal density.