Evolution of the Ge/Si(001) wetting layer during Si overgrowth and crossover between thermodynamic and kinetic behavior -: art. no. 235318

By comparing the scanning tunnel microscope images of the morphological evolution in Ge/Si(001) during Si overgrowth with the results of classical molecular-dynamic simulation and ab initio calculations for Si distribution in the wetting layer, we conclude that the disappearance of the (MxN) reconstruction is determined by Si-Ge intermixing in the third and fourth layers in the Ge wetting layer. The subsequent evolution of the (2xN) pattern, where N increases with further Si deposition, is shown to be produced by Si-Ge intermixing in the second layer. We suggest that this process corresponds to a crossover between thermodynamic behavior and kinetic behavior, which eventually leads to the Si capping.