4H-SiC avalanche photodiode with multistep junctionextensiontermination

4H-SiC avalanche photodiodes (APDs) are fabricated with a multistep junction termination extension. The leakage current density has been dramatically reduced to as low as 1 µA/cm2 and photo-responsivity up to 105 A/W has been achieved. The 4H-SiC APDs can run very stably at power densities up to 104 W/cm2.