Thermodynamic analysis on the stability and evolution mechanism of self-assembled quantum dots

A quantitative thermodynamic model addressing the stability and evolution mechanism during growth process of quantum dots (QDs) in Stranski-Krastanow (SK) system is established by taking into account the thickness-dependent surface energy of wetting layer (WL). It is found that the thickness-dependent surface energy of WL prevents QDs from growing up without limit. The competition between relaxation energy of QDs and thickness-dependent surface energy of WL results in a puzzling phenomenon that WL not only can hardly capture atoms to grow, but also need release atoms into QDs during deposition process and annealing. Agreement between theoretical results and experiments implies that the established thermodynamic model could be expected to be a general approach to pursue the physical mechanisms of self-assembly of quantum dots.