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$8\times8$ 4H-SiC Ultraviolet Avalanche Photodiode Arrays With High Uniformity
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In this letter, high-uniformity $8\times 8$ arrays of 4H-SiC ultraviolet (UV) avalanche photodiode (APD) are reported. In order to improve the detectivity, large active area ( $300~\mu \text{m}$ diameter) was… Click to show full abstract
In this letter, high-uniformity $8\times 8$ arrays of 4H-SiC ultraviolet (UV) avalanche photodiode (APD) are reported. In order to improve the detectivity, large active area ($300~\mu \text{m}$ diameter) was designed for APD pixels. Thick SiNx dielectric deposited by plasma enhanced chemical vapor deposition (PECVD) was adopted as insulator and passivation layer to suppress the reverse leakage current and premature breakdown. Despite the large active area, a high yield of 97% is achieved for the pixels in the 4H-SiC APD array. At room temperature, the pixels exhibit a high gain of over 105, a maximum quantum efficiency of larger than 68% @ 282 nm and an excellent UV/visible rejection ratio of 104. In addition, temperature-stable avalanche breakdown voltage with a positive coefficient of 8 mV/°C is obtained. Furthermore, the APD array shows a high uniformity of breakdown voltage with a standard deviation of 0.1 V for all the 64 pixels, and the dark currents at 95% of breakdown voltage are as low as ~1 nA except for two pixels. The performance improvements indicate a new milestone for 4H-SiC APD arrays in UV imaging applications.
