On the role of interdiffusion during the growth of Ge on Si(001) and Si(111)

The 3D islands of the Stranski-Krastanow-systems Ge/Si(001) and Ge/Si(111), that form either during Ge deposition above 950 K or upon annealing of previously flat and nearly strain-relieved Ge films, are found to be composed of a mixture of Ge and Si, thus pointing to considerable interdiffusion at temperatures above 950 K. Direct measurements of the elastic energy by a cantilever beam device reveal that the Si in-diffusion is mainly driven by the gain in configurational entropy and not by the reduction of misfit-strain.