Epitaxial fabrication of monolayer copper arsenide on Cu(111)**Project supported by the National Key Research & Development Program of China (Grant Nos. 2016YFA0202300 and 2018YFA0305800), the National Natural Science Foundation of China (Grant Nos. 61888102, 11604373, 61622116, and 51872284), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant Nos. XDB30000000 and XDB28000000), and the University of Chinese Academy of

Abstract

We report the epitaxial growth of monolayer copper arsenide (CuAs) with a honeycomb lattice on Cu(111) by molecular beam epitaxy (MBE). Scanning tunneling microscopy (STM), low energy electron diffraction (LEED), x-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) verify the superlattice of monolayer CuAs on Cu(111) substrate. Angle-resolved photoemission spectroscopy (ARPES) measurements together with DFT calculations demonstrate the electronic band structures of monolayer CuAs and reveal its metallic nature. Further calculations show that charge transfer from Cu(111) substrate to monolayer CuAs lifts the Fermi level and tunes the band structure of the monolayer CuAs. This high-quality epitaxial monolayer CuAs with potential tunable band gap holds promise on the applications in nano-electronic devices.