Epitaxial Growth and Structural Properties of Bi(110) Thin Films on TiSe2 Substrates

摘要

We report the growth and structural properties of Bi thin films on TiSe2 substrates by using a low-temperature scanning tunneling microscope. Extended Bi(110) thin films are formed on the TiSe2 substrates and adopt a distorted black-phosphorus structure at room temperature (RT). The diagonal of the Bi(110) rectangular unit cell is parallel to the close-packed direction of the top-layer Se atoms of the TiSe2 substrates, resulting in the formation of a stripe-shaped commensurate moire pattern with a periodicity of similar to 38.5 angstrom at RT. Meanwhile, the charge density wave phase transition of the TiSe2 substrate and the different coefficients of thermal expansion of Bi(110) and TiSe2 lead to the formation of a quasi-hexagonal incommensurate moire pattern with a periodicity of 14.5 angstrom at 77 K. In particular, the combination of domains with twisting angles of 30 degrees or 60 degrees results in the formation of various domain boundaries. Our work is very helpful for understanding and tuning the structural and electronic properties of epitaxial Bi(110) thin films.