Performance of Low-Dark-Current 4H-SiC Avalanche Photodiodes With Thin Multiplication Layer

The authors report on the fabrication and performance of low-dark-current 4H-SiC avalanche photodiodes with a thin 180-nm-thick p ^- multiplication layer. At a photocurrent gain M of 1000, the dark current of a 100-mum-diameter device was 35 pA (0.44 muA/cm²). The peak unity-gain responsivity was 100 mA/W (external quantum efficiency=46%) at lambda=268 nm, and at high gain, a responsivity greater than 10⁷ A/W was achieved. The excess noise factor corresponds to k=0.12. Time-domain pulse measurements indicate an RC-limited unity-gain bandwidth of 300 MHz