MOCVD Growth of Tungsten Ditelluride Thin Films

• Published in: Journal of crystal growth 2024-01, Vol.625, p.127436, Article 127436
• Main Authors: Mc Knight, Thomas V., Choudhury, Tanushree H., Wang, Ke, Bansal, Anushka, Redwing, Joan M.
• Format: Article
• Language: English
• Subjects: A3. Chemical vapor deposition processes; A3. Metalorganic chemical vapor deposition; B1. 2D Materials; B1. Nanomaterials; B1. Tellurides; B1. Transition metal dichalcogenides
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2023.127436

•WTe2 thin films grown on sapphire by Metal Organic Chemical Vapor Deposition MOCVD.•Diethyl tellurium (DETe) and tungsten hexacarbonyl (W(CO)6) precursors.•1 T’ phase WTe2 forms in temperature window between 350 and 500 °C.•Carbon deposition from DETe dominates at higher growth temperatures and pressures.•Nanocrystalline films are largely c-axis oriented with additional twist and tilt. The growth of tungsten ditelluride (WTe2) thin films on c-plane sapphire substrates was demonstrated by metalorganic chemical vapor deposition (MOCVD) using tungsten hexacarbonyl (W(CO)6) and diethyltelluride (DETe) as precursors for W and Te, respectively, in a H2 carrier gas. The effects of substrate temperature, reactor pressure, precursor and carrier gas flow rates, and chalcogen-to-metal ratio on the WTe2 growth rate and film properties were determined. Substrate temperatures less than 500 °C were required to deposit WTe2 which was found to be beneficial to suppress simultaneous carbon deposition from the DETe precursor. The films exhibited a fine-grained morphology independent of growth temperature. The layered crystalline 1 T’ phase of WTe2 was confirmed using high resolution X-ray diffraction (HRXRD) and cross-sectional transmission electron microscopy (TEM) which revealed that the films were predominantly c-axis oriented with in-plane twist. X-ray photoelectron spectroscopy (XPS) demonstrated that the WTe2 films were stable in air for a few days but eventually exhibited oxidation.