We have investigated the electronic structures of single- and double-layered MoS, composing of heterojunction structures such as graphene, MoS, and SiO and MoS and SiO, using scanning photoelectron microscopy. Negative shifts of both core levels and valence bands toward the Fermi energy have been observed. In connection with first-principles calculations, we have confirmed that the direct gap of single-layer MoS is changed to an indirect gap by stacking additional layers via van der Waals interlayer interactions.
- Received 12 April 2011
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