Ohmic contact between titanium and sputtered MoS2 films achieved by forming-gas annealing

Abstract

A molybdenum disulfide (MoS2) film prepared by RF sputtering is considered as the new channel material of MOSFETs. However, it is difficult to achieve a low contact resistance for the metal/sputtered-MoS2 interface, which is essential for achieving high performance characteristics. In this study, we investigated titanium (Ti)/sputtered-MoS2 contact characteristics at various annealing temperatures in forming gas (F.G.) ambient (3% H2 in N2). Ti/sputtered-MoS2 interfaces show the Ohmic contact with F.G. annealing from room temperature to 700 °C, and the maximum currents were obtained at 700 °C. Contact resistance, which is normalized by contact area, decreases with an increase in F.G. annealing temperature above 500 °C. Contact resistances of 10−2–10−3 Ω cm2 were obtained with F.G. annealing at 700 °C even for a low-carrier-density n-type MoS2 film. If high-carrier-density MoS2 films were used as source and drain regions, it is speculated that a low contact resistance can be achieved with Ti/sputtered-MoS2 systems, leading to the realization of high-performance sputtered-MoS2 MOSFETs.