GROWTH AND ATOMIC-STRUCTURE OF EPITAXIAL SI FILMS ON GE(111)

Heteroepitaxial growth by molecular beam epitaxy of thin Si films on t he Ge(111) surface was studied. The surface morphology and atomic stru cture were examined by scanning tunneling microscopy and synchrotron-r adiation photoemission. For submonolayer Si coverages on the Ge(111) s ubstrate at room temperature, the impinging Si atoms condense to form small islands. The areas surrounding the islands remain c(2 x 8). Post annealing or growth at high temperatures causes Si indiffusion and Ge segregation to the surface. Multilayer deposition at high temperature s can be described as a mixed two- and three-dimensional growth. Many small three-dimensional islands are observed on a two-dimensional film . The surface structure of the film shows partial disorder, and the fi lm itself contains numerous defects caused by the lattice mismatch bet ween Si and Ge. The role of the segregated Ge as a surfactant in the g rowth is discussed.