Transistors on two-dimensional semiconductors: contact resistance limited by the contact edges

We report for the first time a TCAD investigation on the spatial distribution of carrier injection at MoS
2
contacts. The proposed semi-classical approach successfully captures the experimentally observed contact behavior. Using the model, we identify that for monolayer and bilayer MoS
2
, the carriers are injected at the edge of the contact metal, resulting in a high contact resistance. The primary cause of this high resistance is carrier depletion under the contacts, which is not alleviated at degenerate doping under the contacts.