Epitaxial growth and air-stability of monolayer Cu2Te**Project supported by the National Key Research & Development Program of China (Grant Nos. 2016YFA0202300 and 2018YF A0305800), the National Natural Science Foundation of China (Grant Nos. 61888102, 11604373, 61622116, and 51872284), the CAS Pioneer Hundred Talents Program, China, the Strategic Priority Research Program of Chinese Academy of Sciences (Grant Nos. XDB30000000 and XDB28000000),

Abstract

A new two-dimensional atomic crystal, monolayer cuprous telluride (Cu2Te) has been fabricated on a graphene-SiC(0001) substrate by molecular beam epitaxy (MBE). The low-energy electron diffraction (LEED) characterization shows that the monolayer Cu2Te forms a superstructure with respect to the graphene substrate. The atomic structure of the monolayer Cu2Te is investigated through a combination of scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations. The stoichiometry of the Cu2Te sample is verified by x-ray photoelectron spectroscopy (XPS) measurement. The angle-resolved photoemission spectroscopy (ARPES) data present the electronic band structure of the sample, which is in good agreement with the calculated results. Furthermore, air-exposure experiments reveal the chemical stability of the monolayer Cu2Te. The fabrication of this new 2D material with a particular structure may bring new physical properties for future applications.