Bi2Te3-Sb2Te3-Bi2Te3 Lateral Heterostructures Grown by Molecular Beam Epitaxy

TL;DR

This paper reports the successful synthesis of Bi2Te3-Sb2Te3-Bi2Te3 lateral heterostructures on hBN using molecular beam epitaxy, demonstrating precise control over interface quality, epitaxial alignment, and exploring their plasmonic and topological properties.

Contribution

The study introduces a novel MBE growth method for periodic lateral heterostructures with controlled interfaces and alignment, advancing 2D material heterostructure fabrication.

Findings

Heterostructures grow epitaxially with <4° misalignment.

Heterostructures are 4-8 nm thick and several hundred nanometers wide.

Plasmonic and topological properties are characterized and analyzed.

Abstract

Lateral in-plane heterostructures enable precise control of electronic properties and quantum effects in 2D materials. However, their periodic synthesis is challenging because it requires precise control to maintain sharp, coherent interfaces and compatible growth conditions across different domains. Herein, we report the successful heteroepitaxial growth of Bi2Te3-Sb2Te3-Bi2Te3 and periodic lateral heterostructures on hexagonal boron nitride (hBN) through in-situ multiple growth steps at different stages using a molecular beam epitaxy (MBE) system. These trilateral heterostructures are fabricated by growing triangular or hexagonal Bi2Te3 islands at the very beginning, with typical sizes of several hundred nanometers, on the single-crystalline hBN, followed by the lateral growth of Sb2Te3 to form bilateral heterostructures, and finally growing Bi2Te3 on the side facets of the bilateral heterostructures. The electron microscopy results confirm the core area as Bi2Te3, the intermediate layer as Sb2Te3, and the outermost region as Bi2Te3. The resulting heterostructures are approximately 4-8 nm thick and several hundred nanometers in lateral dimensions. These heterostructures are found to grow epitaxially on hBN (< +-4 deg misalignment), and the individual layers are strongly epitaxially aligned with each other. The in-plane heterojunctions are analyzed using the aberration-corrected (Cs-corrected) high-angle annular dark-field scanning transmission electron microscopy technique. We have explored and established the plasmonic properties of these fabricated Bi2Te3-Sb2Te3-Bi2Te3 lateral heterostructures. In addition, the electronic states and the topological properties of the few quintuple layers (QLs) (2- to 4-QLs) Bi2Te3-Sb2Te3 lateral periodic heterostructures are investigated by first-principles calculations.