Fabrication of (Bi2)m(Bi2Te3)n superlattice films by Te desorption from a pristine Bi2Te3 film

We fabricated superlattice films composed of Bi2 bilayers (BLs) and Bi2Te3 quintuple layers (QLs) by annealing pure Bi2Te3 films. It was found that Te desorbs from the QL to form the BL with an activation energy of 2.7 eV. Eventually, two distinct stoichiometric phases were formed, Bi1Te1 (QL–BL–QL) and Bi4Te3 (QL–BL), as evidenced by scanning transmission emission microscopy measurements. The surface-state dispersion was measured with angle-resolved photoemission spectroscopy, and the topological nature of each sample is discussed. Our method offers a convenient and simple way to fabricate superlattice films with different topological properties.