The electronic band structure of MoS single crystals has been investigated using angle-resolved photoelectron spectroscopy and first-principles calculations. The orbital symmetry and dispersion of these electronic states responsible for the direct and the indirect electronic band gaps have been unambiguously determined. By experimentally probing an increase of the electronic band gap, we conclude that a MoS (0002) surface localized state exists just below the valence band maximum at the point. This electronic state originates from the sulfur planes within the topmost layer. Our comprehensive study addresses the surface electronic structure of MoS and the role of van der Waals interlayer interactions.
- Received 5 January 2012
©2012 American Physical Society