Interfacial Properties of Monolayer and Bilayer MoS2 Contacts with Metals: Beyond the Energy Band Calculations
Although many prototype devices based on two dimensional (2D) MoS2 have been fabricated and wafer scale growth of 2D MoS2 has been realized, the fundamental nature of 2D MoS2 metal contacts has not been well understood yet. We provide a comprehensive ab initio study of the interfacial properties of a series of monolayer (ML) and bilayer (BL) MoS2 metal contacts (metal Sc, Ti, Ag, Pt, Ni, and Au) A comparison between the calculated and observed Schottky barrier heights (SBHs) suggests that many electron effects are strongly suppressed in channel 2D MoS2 due to a charge transfer. The extensively adopted energy band calculation scheme fails to reproduce the observed SBHs in 2D MoS2 Sc interface. By contrast, an ab initio quantum transport device simulation better reproduces the observed SBH in 2D MoS2 Sc interface and highlights the importance of a higher level theoretical approach beyond the energy band calculation in the interface study. BL MoS2 metal contacts generally have a reduced SBH than ML MoS2 metal contacts due to the interlayer coupling and thus have a higher electron injection efficiency.
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