Hole in Pixel Improves NIR Response

Image Sensors World        Go to the original article...

W&WSens Devices, University California at Davis, and University California at Santa Cruz publish a paper "Single Microhole per Pixel in CMOS Image Sensor with Enhanced Optical Sensitivity in Near-Infrared" by E. Ponizovskaya Devine, Wayesh Qarony, Ahasan Ahamed, Ahmed S Mayet, Soroush Ghandiparsi, Cesar Bartolo-Perez, Aly F Elrefaie, Toshishige Yamada, Shih-Yuan Wang, and 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."

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