Revisiting the van der Waals Epitaxy in the Case of (Bi0.4Sb0.6)2Te3 Thin Films on Dissimilar Substrates

Enhancement of the Surface Morphology of (Bi0.4Sb0.6)2Te3 Thin Films by In Situ Thermal Annealing

The study of the exotic properties of the surface states of topological insulators requires defect-free and smooth surfaces. This work aims to study the enhancement of the surface morphology of optimally doped, high-crystalline (Bi_0.4Sb_0.6)₂Te₃ films deposited by molecular beam epitaxy on Al₂O₃ (001) substrates. Atomic force microscopy shows that by employing an in situ thermal post anneal, the surface roughness is reduced significantly, and transmission electron microscopy reveals that structural defects are diminished substantially. Thence, these films provide a great platform for the research on the thickness-dependent properties of topological insulators.

Advances in Topological Materials: Fundamentals, Challenges and Outlook

The discovery of topological insulators, characterized by an energy gap in bulk electronic band structures and metallic states on boundaries, has greatly inspired studies on the topological properties of the electronic band structures of crystalline materials [...].