Ge adatoms on Si surface (H. J. Gotsis) The study of atomistic processes in the Si-Ge epitaxial growth is of great scientific and technological interest. In particular, a number of fundamental problems related to interface sharpness or ordering during alloy growth have to be explained on a microscopic level. The technological interest in this system is related to the recent progress in the fabrication of the molecular beam epitaxy grown Si/Ge superlattices aimed at the direct gap silicon based material for optoelectronic applications. One of the most fundamental questions is the identification of the binding sites for Ge adatoms on the Si(100) surface and the determination of the activation energy for surface diffusion. For the electronic structure calculation we employ the projector augmented wave (PAW) method, as implemented in the VASP code. Initially we calculate the difference in surface energy for ideal and reconstructed Si(100) surface. The reconstruction will be used as the starting geometry for the Ge adsorption.
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