Alloy-buffer-controlled van der Waals epitaxial growth of aligned tellurene

Group-VI elemental two-dimensional (2D) materials (e.g., tellurene (Te)) have unique crystalline structures and extraordinarily physical properties. However, it still remains a great challenge to controllably grow 2D Te with good repeatability, uniformity, and highly aligned orientation using vapor growth method. Here, we design a Cu foil-assisted alloy-buffer-controlled growth method to epitaxially grow aligned single-crystalline 2D Te on an insulating mica substrate. The in-situ formation of Cu-Te alloy plays a key role on 2D Te growth, alleviating the spatial and temporal non-uniformity of precursor in conventional vapor deposition process. Through transmission electron microscopy (TEM) analysis combined with theoretical calculations, we unveil that the alignment growth of Te in the [110] direction is along the [600] direction of mica, owing to the small lattice mismatch (0.15%) and strong binding strength. This work presents a method to grow aligned high-quality 2D Te in a controllable manner.