Large area growth of layered WSe₂films

Growth of smooth and continuous films of WSe 2 has been demonstrated by employing atomic layer deposition (ALD) on 5 cm × 5 cm substrates. The substrates consisted of silicon wafers with a layer of SiO 2 . The ALD precursors were WCl 5 and H 2 Se. The film properties characterized using Raman spectroscopy and x-ray photoelectron spectroscopy are comparable to those reported for WSe 2 films produced by chemical vapor deposition and exfoliation. Carrier mobilities were determined with back-gated transistors. With Pd contacts, median electron and hole mobilities of 531 cm 2 V −1 s −1 and 354 cm 2 V −1 s −1 , respectively, were measured.