Annealed Ag contacts to MoS2 field-effect transistors

Abstract

Silver contacts to few-layer (5 to 14 layers thick) MoS2 have been studied before and after annealing. Annealing was found to be critical for reducing the contact resistance but did not degrade the operation of field-effect transistors that are part of the test structure. The contact resistance for the as-deposited samples was in the range of 0.8–3.5 kΩ μm. On the other hand, the contact resistance was reduced to 0.2–0.7 kΩ μm, evaluated at a constant sheet resistance of 32 kΩ/□, after annealing at 250 or 300 °C. The reduced contact resistance is attributed to diffusion of Ag into the MoS2 and doping, as supported by further electrical characterization of the contacts and devices.