van der Waals epitaxial growth and characterization of MoSe2 thin films on SnS2

Abstract

A variation on molecular beam epitaxy(MBE), called van der Waals epitaxy, is described where a material with primarily two‐dimensional (2D) bonding is grown on a substrate which also has a 2D structure. Lattice matching difficulties, which limit the choice of materials in MBE of 3D systems, are circumvented since the interlayer bonding is from weak van der Waals interactions. The title system shows a lattice mismatch of 10% yet high quality epitaxial films can be grown. The films were characterized i n s i t u with reflection high energy electron diffraction,Auger electron spectroscopy, and low energy electron loss spectroscopy. Additional characterization after exposure to ambient by x‐ray photoelectron spectroscopy, low energy electron diffraction, transmission electron microscopy confirmed the highly ordered nature of the films. Scanning tunneling microscopy provided real space images of the morphology of the epitaxial layer and showed unusual structures attributed to lattice mismatch.