Direct Synthesis of Large-Scale WTe2 Thin Films with Low Thermal Conductivity

Large-scale, polycrystalline WTe2 thin films are synthesized by atmospheric chemical vapor reaction of W metal films with Te vapor catalyzed by H2Te intermediates, paving a way to understanding the synthesis mechanism for low bonding energy tellurides and toward synthesis of single-crystalline telluride nanoflakes. Through-plane and in-plane thermal conductivities of single-crystal WTe2 flakes and polycrystalline WTe2 thin films are measured for the first time. Nanoscale grains and disorder in WTe2 thin films suppress the in-plane thermal conductivity of WTe2 greatly, which is at least 7.5 times lower than that of the single-crystalline flakes.