Metal/P-type GeSn Contacts with Ultra-low Specific Contact Resistivity

Contact resistance R c in the source/drain (S/D) regions of field-effect transistors (FETs) has increased significantly due to the shrinkage of contact area accompanied with the scaling of device dimensions in the past decades [1] . For the state-of-art transistor technology, the contact area is around 10×10 nm 2 [2] . R c , inversely proportional to the effective contact area, is the main parasitic resistance that limits the on-state current and switching speed of the device in the leading technology. To alleviate the impact of R c , an ultralow specific contact resistivity ρ c of less than 10 −9 Ω-cm 2 is required [3] .