Engineered Electrical Contacts

Contact resistance and current transport are important to nano scale electrical contacts, such as those based on thin films, carbon nanotube (CNT) networks, and novel two-dimensional (2D) materials. Current crowding at the contact edges lead to nonuniform heat deposition, formation of local hotspots, and in the worst scenario, thermal runaway and breakdown of the device. Contact resistance, on the other hand, severely limits the performance of low-dimensional material based electronics. In this study, we propose a method to design nanoscale electrical contacts with controlled current distribution and contact resistance via engineered spatially varying contact layer properties and geometry [1] [2] . From calculations based on transmission line model [3] [4] , we found that the contact current density greatly depends on the properties of the interfacial layer between the two contacting members. The nonuniformity of the current distribution can be reduced significantly by strategically designing the interfacial layer specific contact resistivity ρ c . The acute current crowding in highly conductive ohmic contacts can be reduced greatly by parabolically varying the ρ c along contact length, or by introducing a tunneling layer [5] between the contact members. We also found that the contact resistance for 2D material based Schottky contacts can be reduced significantly by roughness engineering of the interfacial layer [6] .