Topography and structure of ultrathin topological insulator Sb2Te3 films on Si(111) grown by means of molecular beam epitaxy

• Single-crystalline topological insulator Sb2Te3 grown on Si (111) by MBE.
• Formation of twin domains and dislocations determined by XRD and STM.
• Sb/Te accumulation layer at the Sb2Te3/Si interface detected by atom probe tomography.

We have studied the growth process of the topological insulator (TI) Sb2Te3Sb2Te3 on Si(111) by scanning tunneling microscopy. High quality thin films from more than 22 nm down to 1 nm in thickness have been deposited by molecular beam epitaxy. To determine the thickness and domain formation of the films, x-ray reflectivity and x-ray diffraction were utilized. In comparison to previous studies of the TI Bi2Te3Bi2Te3, the growth mechanism of Sb2Te3Sb2Te3 shows a similar transition from nucleation and growth in Sb–Te and Te–Te bilayers, respectively, to mound formation for thicker films. Atom probe tomography measurements reveal a intermixed interface between Sb2Te3Sb2Te3 and Si(111) substrate. These findings can explain the high density of defects and domains.