Engineering of metal-MoS2 contacts to overcome Fermi level pinning

•Interface states in metal-MoS2 are presumably reason for the Fermi Level pinning.•The Fermi level de-pinning could be attained by controlling the distance.•The metal-MoS2 contacts can be engineered by means of the insertion of proper buffer layers and the use of back-gated structures. Fermi level pinning (FLP) in metal-MoS2 contacts induces large Schottky barrier heights which in turn results in large contact resistances. In this work, we made use of Density Functional Theory (DFT) to study the origin of FLP in MoS2 contacts with a variety of metals. We also reported how the Fermi level de-pinning could be attained by controlling the distance between the metal and MoS2. In this respect, the metal-MoS2 contacts can be engineered by means of the insertion of proper buffer layers and the use of back-gated structures. This results in a practically zeroed Schottky barrier heights for some specific metal-MoS2 stacks, which it is crucial to attain Ohmic contacts with low series resistances.