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. 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.