Microstructural characterization of Cr-doped (Bi,Sb)2Te3 thin films

The presence of twins, both tilting and twisting of domains and resulting strain at domain boundaries in magnetically doped topological insulators can significantly modify their band topology and carrier density, and hence their electronic properties. In this paper, we report on a detailed microstructural characterization of Cr-doped (Bi,Se)2Te3 layers grown by molecular beam epitaxy on Si(111). We provide detailed microscopical descriptions of defects present in the films (twins, mosaicity tilt, mosaicity twist), and suggest ways to control their structural quality.