Electrical properties of N₂- and H₂ -annealed bulk MoS₂/metal junctions

We have investigated the electrical transport in symmetric metal-bulk MoS₂-metal junction devices as a function of the temperature in the bias-voltage range between −0.5 V and +0.5 V. Three different types of MoS₂ were: pristine, N₂-annealed and H₂-annealed MoS₂. Metal/MoS₂ contacts were formed by evaporating various metals (Al, Au, Ti and Ni) with different work functions on the surface of MoS₂. The two-terminal current-voltage characteristics were measured in the temperature range from 100 K to 300 K, and the thermal activation energies at the metal-bulk MoS₂ interface were also estimated. The Au/MoS₂ and Ni/MoS₂ junctions exhibit Ohmic behavior (linear current-voltage characteristics) over the entire temperature range, regardless of whether N₂- or H₂-annealing was applied. Al/N₂ annealed MoS₂ and Ti/N₂ annealed MoS₂ junction devices exhibited Schottky behavior (nonlinear current-voltage characteristics) as the temperature was decreased below 150 K. We attribute the different electrical transport properties that were observed to the dissimilar natures of the junction interfaces and to the annealing-induced modification in the Fermi level of MoS₂.