Contact Resistance at MoS2-Based 2D Metal/Semiconductor Lateral Heterojunctions

The contact resistance at lateral 1T-MoS2/2H-MoS2 heterostructures is theoretically studied, using firstprinciples simulations based on density functional theory and the nonequilibrium Green's function method. The computed contact resistance lies between 30 and 40 k Omega mu m and is weakly dependent on the contact edge symmetry (armchair or zigzag). These values are about 2 orders of magnitude larger than the experimental ones reported recently on MoS2-based metal/semiconductor lateral heterojunctions. This discrepancy can be explained by considering the interaction of 1T-MoS2 with various chemical species (H, Li, or H2O) present during the local transformation of semiconducting 2H-MoS2 into metallic 1T-MoS2. The functionalization of 1T-MoS2 by these atoms or molecules results in the decrease of its workfunction, leading to contact resistances in the range of few hundred Omega mu m.