Improved performance of SiC radiation detectors due to optimized ohmic contact electrode by graphene insertion

Abstract

SiC as a typical wide bandgap semiconductor has exhibited potential application in alpha particle detectors. However, due to the comparatively high annealing temperature required for traditional fabrication technique of ohmic electrode, it is easy to excite impurities in the SiC epilayer, which act as scattering centers result in the declined device performance. In present work, a graphene layer is inserted between metal ohmic electrode and SiC. The graphene promotes the formation of carbon compounds and thus decreases ohmic contact resistance. Meanwhile, due to the Fermi level adjustable of graphene by external bias, the barrier of interface at graphene insert layer is enlarged at reverse bias. The built-in field accelerates the separation of photo-generated electron-hole pairs. As a result, the graphene inserted device annealed at 400 °C achieved a 3.9%@-40 V energy resolution, and the device even without annealing achieved a 4.4%@-40 V energy resolution for 239Pu alpha source, which are both better than that of traditional device without graphene layer annealed at 880 °C (6%@-40 V). The detailed mechanism has been discussed and suggested. Present work provides an effective strategy to improve device performance.