The promised performance of monolayer molybdenum disulfide (MoS2)-based devices is hindered by the high electrical resistance at the metal-MoS2 contact. Benefitting from the metallic phase of MoS2, 1T-MoS2 is considered a potential electrode material for the semiconducting 2H-MoS2. In this paper, we report a comparative study of the allotropic 1T/2H MoS2 contact with different contact types. The edge-contact interface has a low tunnel barrier, high charge density, and even Ohmic contact with no Schottky barrier, which implies that this contact may overcome the resistance limit for the electrode-MoS2 contact. The outstanding interface properties of the 1T/2H MoS2 edge contact originate from the excess in-plane dangling bonds in the edge position. Based on our results, the edge-contact model is ideal for the 1T/2H MoS2 contact and may solve the problem of MoS2 contact resistance.

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High-k dielectric materials are indispensable as gate layers for micro- and nano-electronic devices. Using first-principles calculations and non-equilibrium Green's function simulations, we studied the electrical transport characteristics of p-type and n-type monolayer MoS2 field effect transistors (FETs) under various gate dielectric environments. We found that the intrinsic dielectric property of the gate insulator played an important role in the transport performance of nanodevices. For both types of MoS2 FETs, a high-k gate insulator enhances the current on/off ratio and reduces the subthreshold swing by properly shifting the valence (p-type) or conduction (n-type) bands around the bias energy window, which has benefits for the design of MoS2-based short-channel nanodevices in the future.

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