Making a metal contact to the two-dimensional semiconductor MoS2 without creating a Schottky barrier is a challenge. Using density functional calculations we show that, although the Schottky barrier for electrons obeys the Schottky-Mott rule for high work function (≳4.7 eV) metals, the Fermi level is pinned at 0.1-0.3 eV below the conduction band edge of MoS2 for low work function metals, due to the metal-MoS2 interaction. Inserting a boron nitride (BN) monolayer between the metal and the MoS2 disrupts this interaction, and restores the MoS2 electronic structure. Moreover, a BN layer decreases the metal work function of Co and Ni by ∼2 eV, and enables a line-up of the Fermi level with the MoS2 conduction band. Surface modification by adsorbing a single BN layer is a practical method to attain vanishing Schottky barrier heights.
@article{arxiv.1501.02130,
title = {Controlling the Schottky barrier at MoS2|metal contacts by inserting a BN monolayer},
author = {Mojtaba Farmanbar and Geert Brocks},
journal= {arXiv preprint arXiv:1501.02130},
year = {2015}
}