Low dark current 4H-SiC avalanche photodiodes

The fabrication and characterisation of low dark current 4H-SiC avalanche photodiodes is reported. Current–voltage characteristics for a 100 µm-diameter device indicate that near breakdown, for a photocurrent gain greater than 103, the dark current is less than 2 nA. The dark current is dominated by surface leakage at the mesa sidewall. Significant reduction of the dark current has been achieved by improved sidewall passivation.