The effects of surface bond relaxation on electronic structure of Sb2Te3 nano-films by first-principles calculation

The effects of vertical compressive stress on Sb2Te3 nano-films have been investigated by the first principles calculation, including stability, electronic structure, crystal structure, and bond order. It is found that the band gap of nano-film is sensitive to the stress in Sb2Te3 nano-film and the critical thickness increases under compressive stress. The band gap and band order of Sb2Te3 film has been affected collectively by the surface and internal crystal structures, the contraction ratio between surface bond length of nano-film and the corresponding bond length of bulk decides the band order of Sb2Te3 film.