Comparative analysis of pyramidal and wedge-like quantum dots formation kinetics in Ge/Si(001) system

In this work complex mathematical model for calculation of dependencies on growth conditions of parameters of self-organized quantum dots (QDs) of Ge on Si grown by the method of molecular beam epitaxy (MBE) is described. Calculations on pyramidal and elongated islands formation energies in Ge/Si(001) system with respect to surface energy, elastic strains relaxation and attraction of atoms to substrate decreasing are done. On the basis of well-known model based on generalization of classical nucleation theory it is shown that wedge-like clusters form later than pyramidal but begin to dominate in the QDs massive on the later stages of growth. Conclusions from the described theory correspond to the experimental observations.