Manipulations of densities and sizes during self-assembling quantum dots in metal-organic vapour phase epitaxy

Densities and sizes of self-assembled S-dimensional islands were studied in dependence of their deposition conditions. The materials system for more detailed studies was InP/GaAs, deposited by low-pressure metal-organic vapour phase epitaxy (MOVPE). The densities of stable islands follow very well the simple proportionality rho = const (.) R/D, where R = deposition rate and D = the temperature dependent surface diffusion coefficient. The sizes of the a-dimensional islands show inverse behaviour, what is to explain as an effect of distribution of the available material over the number of islands present at the surface. The bimodality in the shapes of 3-dimensional islands of InP on GaAs is strongly affected by deposition temperature and deposition rate. High temperatures/low deposition rates favour the formation of an almost pure population of fully developed islands with high aspect ratios and steep {111} and (110) facets. Low temperatures and high deposition rates favour the population of small, low aspect ratio islands with mow Bat facets. A comparison with other Stranski-Krastanow systems shows in general similar dependencies.