Molecular beam epitaxial growth of Sb2Te3–Bi2Te3 lateral heterostructures

Abstract We report on heteroepitaxial growth of Sb 2 Te 3 –Bi 2 Te 3 lateral heterostructures using molecular beam epitaxy. The lateral heterostructures were fabricated by growing Bi 2 Te 3 islands of hexagonal or triangular nanostructures with a typical size of several 100 nm and thickness of ∼15 nm on graphene substrates and Sb 2 Te 3 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 Bi 2 Te 3 and the outer Sb 2 Te 3 was formed laterally on the graphene in an epitaxial manner. The interface between Bi 2 Te 3 and Sb 2 Te 3 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 Sb 2 Te 3 on Bi 2 Te 3 , corroborating perfect lateral heterostructure formation. In addition, we investigated the topological properties of Sb 2 Te 3 –Bi 2 Te 3 lateral heterostructures using first-principles calculations.