Molecular beam epitaxial step-edge growth of Bi2Te3/multi-stepped Sb2Te3 nanoplate hetero-structures

Abstract

We report the synthesis of multiple Bi₂Te₃ shells on multi-stepped Sb₂Te₃ nanoplates using molecular beam epitaxial (MBE) step-edge growth. For the growth of Bi₂Te₃/Sb₂Te₃ hetero-structures, multi-stepped Sb₂Te₃ nanoplates with stair-like morphology following layer-by-layer (LBL) growth mode were obtained by optimizing the growth temperature, and the growth of Bi₂Te₃ on the step-edges of the Sb₂Te₃ nanoplates was followed. Width of Bi₂Te₃ on the Sb₂Te₃ nanoplates was controlled by changing the growth time. Structural properties of the hetero-structures were investigated using aberration-corrected (C_s-corrected) high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), revealing the interface between Sb₂Te₃ and Bi₂Te₃. In-plane epitaxial relation at the interface was confirmed using fast Fourier transforms (FFTs). Compositional analysis of Bi₂Te₃ and Sb₂Te₃ was verified through energy-dispersive X-ray spectroscopy. Furthermore, we performed density functional theory (DFT) calculations to confirm the preferential growth of Bi₂Te₃ on the step-edges of Sb₂Te₃. By forming multi-stepped core structure, it would be feasible to create various integrated hetero-structures.