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15 February 2012 CMOS BDJ photodiode for trichromatic sensing
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Proceedings Volume 8298, Sensors, Cameras, and Systems for Industrial and Scientific Applications XIII; 82980V (2012)
Event: IS&T/SPIE Electronic Imaging, 2012, Burlingame, California, United States
A novel method for achieving trichromatic color detection using a single photodetector with less than three p-n junctions is presented. This new method removes the constraints of color sensing in buried-double-junction (BDJ) photodiode, eliminates the need for a priori light source knowledge or for changing color intensity. After using a single visible light optical filter to block irradiance external of visible spectrum, the color detection is achieved by taking the difference in depletion region photocurrent generated by different reverse bias voltages. This "difference output" effectively forms the "third" optical wavelength specific depletion region required for trichromatic color sensing. This method is based on exploiting the relationship between photon absorption and photon penetration depth of silicon, and the basic property of p-n junction photodiode which states that only photons absorbed within depletion region generate current. The theory is validated experimentally using BDJ photodiodes fabricated through MOSIS Inc. in the AMI-ABN 1.5um technology and ON-SEMI 0.5um technology. A commercial p-i-n photodiode is also being investigated for contrast and comparison.
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Lien Tu, S. V. Setlur Nagesh, ZhenHong Fu, and Albert H. Titus "CMOS BDJ photodiode for trichromatic sensing", Proc. SPIE 8298, Sensors, Cameras, and Systems for Industrial and Scientific Applications XIII, 82980V (15 February 2012);

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