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.