Electrical properties of N-2- and H-2 -annealed bulk MoS2/metal junctions

Abstract

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, N-2-annealed and H-2-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 N-2- or H-2-annealing was applied. Al/N-2 annealed MoS2 and Ti/N-2 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.