Fermi Level Pinning at the Interface of Molybdenum Based Chalcogenides and Metals

MoS$_{2}$ and MoTe$_{2}$ as the layered two dimensional materials have a sizable band gap suitable for future semiconductor application. However, their Schottky/ohmic contact engineering is found difficult to perform when varying contact metals due to Fermi level pinning at their metal interface. In this work, we investigate Schottky barrier heights at the interfaces formed between mono- or bi-layer MoS$_{2}$, MoTe$_{2}$ and Ti, Cr, Au, Pd. By varying temperature in the range from 200 to 500 K, we obtained their current -- voltage and hysteresis characteristics so as to determine accurate Schottky barrier heights. It is found that the Pd contact with MoS$_{2}$ and MoTe$_{2}$ shows the most pronounced Fermi level pinning; -0.8 and -1.2 eV respectively. Furthermore, the pinned energy level is found to be located near the conduction band edge for MoS$_{2}$ whereas it is near the intrinsic level for MoTe$_{2}$. These results are found to be crucial to understand the Fermi level pinning mechanism of two dimensional materials, which can be used for developing future MoS$_{2}$ and MoTe$_{2}$ based transistor devices.