Band Structure Characterization Of Ws2 Grown By Chemical Vapor Deposition

Growth by chemical vapor deposition (CVD) leads to multilayer WS2 of very high quality, based on high-resolution angle-resolved photoemission spectroscopy. The experimental valence band electronic structure is considered to be in good agreement with that obtained from density functional theory calculations. We find the spin-orbit splitting at the (K) over bar point to be 420 +/- 20 meV with a hole effective mass of -0.35 +/- 0.02 m(e) for the upper spin-orbit component (the branch closer to the Fermi level) and -0.4360.07 m(e) for the lower spin-orbit component. As predicted by theory, a thickness-dependent increase of bandwidth is observed at the top of the valence band, in the region of the Brillouin zone center. The top of the valence band of the CVD-prepared films exhibits a substantial binding energy, consistent with n-type behavior, and in agreement with transistor characteristics acquired using devices incorporating the same WS2 material. Published by AIP Publishing.