Growth processes in the initial stage of Ge films on (811)Si surfaces by GeH4 source molecular beam epitaxy

The growth process in the initial stage of growth of Ge films on (811)Si substrate surfaces by GeH4 source molecular-beam epitaxy has been studied by in situ reflection high-energy electron diffraction observation. It has been found that a strained film by the monolayer overgrowth mode is formed initially with an epitaxial relationship of the parallel orientation, and that plate-shaped Ge islands with (811) facets are grown early in the growth, but that the predominant facet changes to {311} and the (100) planes with further growth. These growth processes are similar to those of Ge films on (100)Si surfaces reported previously. It is concluded that Ge islands with {811} facets are energetically stable in the initial stage of the island growth on the (811)Si surfaces as well as on the (100)Si surfaces.