Proton Irradiation of 4H-SiC Ultraviolet Single Photon Avalanche Diodes

The effects of proton irradiation on uv 4H-SiC single photon avalanche photodiodes (SPADs) are reported. The SPADs, grown by chemical vapor deposition, were designed for uv operation with dark count rates (DCR) of about 30 kHz and single photon detection efficiency (SPDE) of 4.89%. The SPADs were irradiated with 2 MeV protons to a fluence of 10(12) cm(-2). After irradiation, the I-V characteristics show forward voltage (< 1.9 V) generation-recombination currents 2 to 3 times higher than before irradiation. Single photon counting measurements imply generation-recombination centers created in the band gap after irradiation. For threshold voltage ranging from 23 to 26 mV, the 4H-SiC SPAD showed low DCR (< 54 kHz) and high SPDE (> 1%) after irradiation. The SPADs demonstrated proton radiation tolerance for geosynchronous space applications.