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Single Microhole per Pixel in CMOS Image Sensor with Enhanced Optical Sensitivity in Near-Infrared
preprintposted on 2023-11-30, 21:00 authored by E. Ponizovskaya Devine, Wayesh Qarony, Ahasan Ahamed, Ahmed S Mayet, Soroush Ghandiparsi, Cesar Bartolo-Perez, Aly F Elrefaie, Toshishige Yamada, Shih-Yuan Wang, M. Saif Islam
Silicon photodiode based CMOS sensors with backside-illumination for 300 to 1000 nm wavelength range were studied. We showed that a single hole in the photodiode increases the optical efficiency of the pixel. In near-infrared wavelengths, the enhancement allows 70% absorption in a 3 microns thick Si. It is 4x better than for the flat pixel. We compared different shapes and sizes of single holes and holes arrays. We have shown that a certain size and shape in single holes pronounce better optical efficiency enhancement. The crosstalk was successfully reduced with trenches between pixels. We optimized the trenches to achieve minimal pixel separation for 1.12 microns pixel.