Although many prototype devices based on two-dimensional (2D) MoS2 have beenfabricated and wafer scale growth of 2D MoS2 has been realized, the fundamentalnature of 2D MoS2-metal contacts has not been well understood yet. We provide acomprehensive ab initio study of the interfacial properties of a series ofmonolayer (ML) and bilayer (BL) MoS2-metal contacts (metal = Sc, Ti, Ag, Pt,Ni, and Au). A comparison between the calculated and observed Schottky barrierheights (SBHs) suggests that many-electron effects are strongly suppressed inchannel 2D MoS2 due to a charge transfer. The extensively adopted energy bandcalculation scheme fails to reproduce the observed SBHs in 2D MoS2-Scinterface. By contrast, an ab initio quantum transport device simulation betterreproduces the observed SBH in the two types of contacts and highlights theimportance of a higher level theoretical approach beyond the energy bandcalculation in the interface study. BL MoS2-metal contacts have a reduced SBHthan ML MoS2-metal contacts due to the interlayer coupling and thus have ahigher electron injection efficiency.
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