Moiré-pattern-modulated electronic structures in Sb₂Te₃/graphene heterostructure

Moiré superlattice has recently been found in topological insulators, which can lead to periodic modulation on the electronic structure. In this work, we report the low-temperature scanning tunneling microscopy study of Sb₂Te₃ films grown on graphitized 4H-SiC. We find that substrate temperature can strongly influence the rotation angles between Sb₂Te₃ film and graphene substrate. Three kinds of moiré patterns are observed at the first quintuple layer Sb₂Te₃ film under different substrate temperatures. One shows complicated patterns with a rotation angle of nearly 0° relative to the substrate, another just exhibits simple 1 × 1 structure with a rotation angle of 30°. Other rotation angle like 8.2° is observed at higher substrate temperature as well, which is relatively rare. Comparison of the dI/dV curves from Sb₂Te₃ films with different moiré patterns indicates that the superstructure can offer degrees of freedom in tailoring electronic structure. This work may stimulate the further study on the moiré modulation to the electronic properties of topological insulators.