Centimeter-Scale, Large-Area, Few-Layer 1T′-WTe2 Films by Chemical Vapor Deposition and Its Long-Term Stability in Ambient Condition

WTe2 shows unique properties different from sulfides and selenides. Large-area, uniform few-layer 1T′ phase WTe2 and long-term stability are essential for fundamental studies and applications of WTe2. Here, centimeter-scale, large-area, uniform few-layer 1T′-WTe2 films are prepared by a facile, low-temperature, chemical vapor deposition (CVD) method and the long-term stability of such CVD-grown 1T′-WTe2 up to 30 days in ambient condition is studied for the first time. Raman spectroscopy and transmission electron microscopy reveal the high quality of WTe2. The thickness of few-layer WTe2 can be well tuned, and thickness-dependent Raman spectra are observed. The electrical and quantum electronic transport properties are found to be highly influenced by air exposure with different exposure times under ambient condition. The conductivity decreases by about 10 times with exposure, whereas weak antilocation behavior is observed in both pristine and air-exposed samples for 30 days. Surface-oxidization-induced magnetoresistance enhancement up to 30% is discovered unexpectedly.