Contact Extensions Over a High-k Dielectric Layer for Surface Electric Field Mitigation in High Power 4H-SiC Photoconductive Switches

We focus on a simulation study to probe the mitigation of electric fields, especially at the edges of metal contacts to SiC-based photoconductive switches. Field reduction becomes germane given that field-induced failures near contacts have been reported. A dual strategy of extending metal contacts to effectively spread the electric field over a larger distance and to employ HfO2 as a high-k dielectric, is discussed. Simulation results show that peak electric fields can be lowered by up to ∼67% relative to a standard design. Finally, our calculations predict that the internal temperature rise for a ∼7-ns laser pulse and applied voltages around 20 kV (typical experimental values) would also be effectively controlled.