Texture of Ge on SrTiO3 (001) substrates: Evidence for in-plane axiotaxy

Abstract

We report the first experimental evidence of the formation of an axiotaxial texture in a semiconductor/oxide structure, namely Ge deposited by molecular beam epitaxy on a SrTiO3 substrate. The texture of the deposit is carefully analyzed based on X-ray pole figure measurements. We show in particular that the axiotaxial texture is not random, but that the deposit presents a limited number of well defined crystal orientations along axiotaxy locus. We also evidence the presence of twinned zones in the Ge crystal, and we discuss their experimental signature regarding that of the axiotaxy texture. In the end, we show that interface dangling bonds are the main parameter driving Ge crystal orientation, and we compare their influence to that of epitaxial misfit.