Study on non-linearity response of 4H-SiC APD

UV photon counting detection technology based on 4H-SiC Avalanche photodiodes (APDs) has been widely used in virus inactivation system, quantum communication and other UV detection fields. When the ultraviolet signal is enhanced, the detection accuracy will also decrease due to the nonlinear characteristics of the photoelectric response. Therefore, the physical mechanism and nonlinear error source of the photoelectric response of 4H-SiC APD were analysed, and a photoelectric response characteristic testing system was built. The theoretical and experimental results show that the photocurrent increases linearly when the incident photon number is high, and the multi-photon incident results in the nonlinear phenomenon of photon count. Reducing device bias and increasing threshold voltage can significantly improve the nonlinear phenomenon of photoelectric response, and the maximum linear operating range of the device can be extended from 10 ⁷s ^-1 to more than 10 ⁹s ^-1.