Large area van der Waals epitaxy of high-mobility two-dimensional tellurium on silicon

The two-dimensional form of tellurium, named tellurene, holds intriguing properties for a broad range of applications. Here, the large area growth by molecular beam epitaxy of tellurium on Sb-passivated Si(111) is demonstrated. The influence of growth temperature and film thickness on the material properties was investigated. At optimized conditions, the two-dimensional growth of Te films as thin as 4 nm is established. The epilayers possess a (101 & strns;\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar{1}$$\end{document}0) surface orientation, with the Te chiral chains lying parallel to the surface plane. The van der Waals epitaxy occurs with the formation of a Sb2Te3 interlayer, as confirmed by transmission electron microscopy. Grazing incidence diffraction shows a discrete set of domains with in-plane rotation angles, which result in the alignment of Te lattice planes of neighbouring domains. The high hole mobility of epitaxial tellurium at room temperature is proven by Hall effect measurements. Optical spectroscopy measurements strongly support the electrical data. The thickness-dependent vibrational properties of the material were studied by Raman spectroscopy: by scaling down the film thickness, characteristic features of few-layer tellurium are observed. Hence, the present study opens the way for the integration of two-dimensional tellurium on silicon and the design of novel heterostructures of layered tellurides.