Kapildeb Dolui, Ivan Rungger, Stefano Sanvito
Ab-initio density functional theory calculations are performed to study the electronic properties of a MoS2 monolayer deposited over a SiO2 substrate in the presence of interface impurities and defects. When MoS2 is placed on a defect-free substrate the oxide plays an insignificant role, since the conduction band top and the valence band minimum of MoS2 are located approximately in the middle of the SiO2 band-gap. However, if Na impurities and O dangling bonds are introduced at the SiO2 surface, these lead to localized states, which modulate the conductivity of the MoS2 monolayer from n- to p-type. Our results show that the conductive properties of MoS2 deposited on SiO2 are mainly determined by the detailed structure of the MoS2 /SiO2 interface, and suggest that doping the substrate can represent a viable strategy for engineering MoS2 -based devices.
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http://arxiv.org/abs/1301.2491
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