Site Preference of Se and Te in Bi₂Se_{3 − x}Te_x Thin Films

Abstract

The ternary topological insulators Bi2Se3 − x Te x have attracted a great deal of attention due to their exotic physical and chemical properties. While most of the studies focus on the properties of these ternary TIs, limited research was performed to investigate the dynamic atomic stack of its crystal structure. We prepared high-quality Bi2Se3 − x Te x thin films on GaAs(111)B substrates using molecular beam epitaxy, characterized with Raman spectroscopy, x-ray diffraction and photoelectron spectroscopy. It is found that when Se is replaced by Te, the preferred substituting sites are the middle layer at 0 < x < 1, and this is also valid for Se substituting Te at 2 < x < 3. In the middle region, the substituting atoms prefer to go to the first and the fifth layer.