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 d etailed studies was InP/GaAs, deposited by low-pressure metal-organic vapou r phase epitaxy (MOVPE). The densities of stable islands follow very well t he simple proportionality rho = const (.) R/D, where R = deposition rate an d 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 island s present at the surface. The bimodality in the shapes of 3-dimensional isl ands of InP on GaAs is strongly affected by deposition temperature and depo sition rate. High temperatures/low deposition rates favour the formation of an almost pure population of fully developed islands with high aspect rati os and steep {111} and (110) facets. Low temperatures and high deposition r ates 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.