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

Moire 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 moire 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 moire patterns indicates that the superstructure can offer degrees of freedom in tailoring electronic structure. This work may stimulate the further study on the moire modulation to the electronic properties of topological insulators.