Gradual Edge Contact between Mo and MoS Formed by Graphene-Masked Sulfurization for High-Performance Field-Effect Transistors.

Two-dimensional materials have attracted great attention for their outstanding electronic properties. In particular, molybdenum disulfide (MoS) shows great potential as a next-generation semiconductor due to its tunable direct bandgap with a high on-off ratio and extraordinary stability. However, the performance of MoS synthesized by physical vapor deposition has been limited by contact resistance between an electrode and MoS, which determines overall device characteristics. Here, in order to reduce the contact resistance, we use in situ sulfurization of Mo by HS gas treatment masked by a patterned graphene gas barrier, so that the Mo channel area can be selectively formed, resulting in a gradual edge contact between Mo and MoS. Compared with field-effect transistors with a top contact between the Au/Ti electrode and the MoS channel, a gradual edge contact between the Mo electrode and the MoS channel provides a considerably enhanced electrical performance.