W Te ₂ thin films grown by beam-interrupted molecular beam epitaxy

Abstract The growth of WTe ₂ thin films by molecular beam epitaxy is demonstrated for the first time on a variety of 2D substrates including MoS ₂ , Bi ₂ Te ₃ , and graphite. We demonstrate that beam interruption of the metal source enables the growth of crystalline WTe ₂ films in the distorted octahedral (1T′) phase. As a result of the van der Waals nature of this material, a sharp interface between the WTe ₂ thin film and the substrate is shown with no evidence of misfit dislocations. In addition, the buckled structure expected for the semi-metallic 1T′ phase is observed with transmission electron microscopy. Raman spectroscopy further confirms the growth of the 1T′ phase and x-ray photoelectron spectroscopy shows the films to be stoichiometric and semi-metallic as expected.