Study on the resistance distribution at the contact between molybdenum disulfide and metals.

Contact resistance hinders the high performance of electrical devices, especially devices based on two-dimensional (2D) materials, such as graphene and transition metal dichalcogenide. To engineer contact resistance, understanding the resistance distribution and carrier transport behavior at the contact area is essential. Here, we developed a method that can be used to obtain some key parameters of contact, such as transfer length (Lt), sheet resistance of the 2D materials beneath the contacting metal (Rsh), and contact resistivity between the 2D materials and the metal electrode (ρc). Using our method, we studied the contacts between molybdenum disulfide (MoS2) and metals, such as titanium and gold, in bilayer and few-layered MoS2 devices. Especially, we found that Rsh is obviously larger than the sheet resistance of the same 2D materials in the channel (Rch) in all the devices we studied. With the increasing of the back-gate voltage, Lt increases and Rsh, ρc, Rch, and the contact resistance Rc decrease in all the devices we studied. Our results are helpful for understanding the metal–MoS2 contact and improving the performances of MoS2 devices.