Successful development of high-performance color filter-free image sensor by DGIST

The image sensor used currently contains a color filter to accurately take the photo of an object. However, it has been pointed out for its shortcomings such as the declined efficiency of an electronic device, increased processing cost, and thick volume of sensor caused by the insertion of color filter.

By replacing the transparent electrode of the existing image sensor with the electrode of an interferometer structure, the research team enabled the image sensor to perform both the roles of electrode and color filter and succeeded in developing an image sensor prototype by applying this.

The research team applied the permeation of light in certain wavelength through the multiple interference in the interferometer structure. By adjusting the components and thickness of the interferometer electrode in particular, the team increased the color selectivity of Red (R) / Green (G) / Blue (B) without sacrificing electric conductivity.

The team also developed color-selective photodiodes by applying the interferometer electrode developed to a high-performance photodiode structure, which absorbs entire visible light range and produced an image sensor where these photodiodes are arranged in 10x10 pixel. The image sensor is applicable to flexible wearable devices because the thickness of its unit pixel is less than 800nm.

Professor Dae Sung Chung explained the significance of this research by stressing that "This is a technological innovation that overcame the structural limitations of existing image sensor, by achieving both color-free and thin thickness image sensor. This technology will be expanded to applications in mobile devices using not only visible rays but also near-infrared and infrared color-free image sensor."

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This research was performed with the support from the Ministry of Science and ICT as well as the Basic Research Project (mid-level research) and Core Space Technology in National Research Foundation of Korea Basic, and it was published online on 'ACS Nano', a world-renowned academic journal in material science, on February 1.