Influence of plasma-induced phase transition on contact resistance in MoTe2 with varying thickness

Two-dimensional layered crystals have distinct advantages for short channel devices, however, the large contact resistance is a major obstacle to their utilization. Here we present a method to transform two-dimensional layered crystals of MoTe2 with different thicknesses from the 2H phase to the 1T phase using hydrogen plasma treatment. We analyze the influence of this phase change on the contact resistance by using Raman spectroscopy and the output and transfer characteristics of electrical devices. Results show that the contact resistance is significantly reduced to 1.2 K omega, and is dependent on the number of layers, with thicker layers having lower contact resistance. AFM characterization has shown that plasma treatment can induce phase transitions in the all layers of MoTe2 nanosheet, resulting in the total resistance being equivalent to the parallel connection of the resistance of each layer. Our findings suggest that the thickness of MoTe2 has a strong effect on its electrical properties.