Photo-Electric response of 4H-SiC APDs at High-Level incident flux

In many applications, the highest and lowest detectable flux are both important for single photon avalanche photodiodes (APDs). The photocurrent and single-photon-counting performance of 4H-SiC APDs are investigated under a wide-range incident flux. Experimental results show that the photocurrent is sub-linearly with the incident photon rate at high-level incident flux. In addition, the ratio of photon count rate to dark count rate is non-monotonic when the incident flux increases. The highest detectable flux of the 4H-SiC APD can be extended from 3 × 103 photons/s·μm2 to more than 4 × 104 photons/s·μm2 by reducing the threshold voltage and increasing the reverse voltage.