Study On 4H-SiC SAM-APD Structure UV Detector

The ultraviolet detectors have many applications in chemical sensing, flame detection and missile plume sensing in harsh and severe radiation environment. Due to the wide bandgap of 4H-SiC, photo detectors utilising this material should have the advantage of a good visible-blind/solar-blind performance. The basic parameters and the comparison of the characteristics of 4H-SiC APD are presented. This paper constructed a SAM-APD physical model based on drifting-diffusion theory, simulated the bias I-V character, the spectral responsivity, quantum efficiency are investigated in this thesis. The affection of the UV detector responsivity with different SAM-APD thickness of each epilayers has been simulated by orthogonal experiment. The analysis showed that the varying of p+ layer generated significant effects on APD responsivity, n layer standed on the second and n- layer showed unconspicuous. Based on the conclusion above, the research fulfilled an ameliorated SAM-APD UV detector, enhanced the spectral responsivity of UV detectors. A layout of the device has been designed and then the process for fabrication and its parameters are discussed. Benefiting from decreasing the window area of device, the greatly increasing trend of surface dark current is restrained and the design requirement of UV detector is met.A new device modeling for 4H-SiC SAM-APD ultraviolet photodetector presented in this thesis provides some design guidance for its further research.