Weak ultraviolet light detection has important application prospects in fields such as fire warning, corona detection, and deep space detection. Avalanche photodiodes (APDs) have the advantages of high quantum efficiency, high gain, and ease of integration, making it more suitable for detecting ultraviolet light. In terms of materials, compared with Si, wide bandgap semiconductor materials represented by GaN and SiC can effectively shield the influence of visible and infrared light, demonstrating significant advantages in the field of ultraviolet detection. Among them, 4H-SiC has the advantages of high thermal conductivity, high critical electric field, and high ratio of hole to electron ionization coefficient, making it an ideal material for making avalanche ultraviolet photodetectors. PAM-XIAMEN can offer 4H-SiC epiwafer for APD fabrication. The detailed epi-structures of 4H-SiC APD are as follows:
1. 4H-SiC APD Wafer Structure
No. 1
| Epi Structure | Thickness | Doping Concentration |
| p+ cap layer | 0.1um | 2×1019cm-3 |
| p epilayer | 0.2um | 2×1018cm-3 |
| p- epilayer | 0.5um | 3×1015cm-3 |
| n+ epilayer | 2um | 1×1019cm-3 |
| n+ 4H-SiC substrate |
No. 2
| Epi Structure | Thickness | Doping Concentration |
| n+ contact layer | 0.15um | 1×1019cm-3 |
| n epilayer | 0.2um | 1×1018cm-3 |
| n- avalanche multiplier layer | 0.78um | 1×1015cm-3 |
| p epilayer | 10um | 3×1018cm-3 |
| n+ 4H-SiC substrate |
Research has shown that the 4 ° off axis growth of SiC wafer and the anisotropy of carrier mobility cause lateral drift of photo generated carriers along the [1120] direction when collected by the electrode. The difference in the collection efficiency of photo generated carriers by the electrode in the [11¯20] and [¯1¯120] directions results in non-uniform carrier accumulation, which subsequently leads to non-uniform electric field shielding within the APD, and ultimately leads to non-uniform avalanche breakdown of the device. Therefore, deepening the understanding of device avalanche states is beneficial for designing SiC APD device structures more reasonably, and provides an important direction for improving the single photon detection efficiency of devices.
2. Applications of SiC Avalanche Photodiodes
APDs have the advantages of high internal gain and high responsiveness, which can effectively detect weak signals and improve the signal-to-noise ratio of devices. The ultraviolet detector based on SiC APD array has broad application prospects in fields such as fire warning, environmental detection, ultraviolet communication, astronomical research, and medical applications.
For more information, please contact us email at victorchan@powerwaywafer.com and powerwaymaterial@gmail.com.