Molecular beam epitaxial growth of Sb2Te3-Bi2Te3 lateral heterostructures

We report on heteroepitaxial growth of Sb2Te3-Bi2Te3 lateral heterostructures using molecular beam epitaxy. The lateral heterostructures were fabricated by growing Bi2Te3 islands of hexagonal or triangular nanostructures with a typical size of several 100 nm and thickness of similar to 15 nm on graphene substrates and Sb2Te3 laterally on the side facets of the nanostructures. Multiple-step processes with different growth temperatures were employed to grow the lateral heterostructures. Electron microscopy techniques indicate that the inner region is Bi2Te3 and the outer Sb2Te3 was formed laterally on the graphene in an epitaxial manner. The interface between Bi2Te3 and Sb2Te3 from planar and cross-sectional views was studied by the aberration-corrected (C (s)-corrected) high-angle annular dark-field scanning transmission electron microscope technique. The cross-sectional electron microscopy investigation shows no wetting layer of Sb2Te3 on Bi2Te3, corroborating perfect lateral heterostructure formation. In addition, we investigated the topological properties of Sb2Te3-Bi2Te3 lateral heterostructures using first-principles calculations.