Photosensitive Pixel

A photosensitive pixel is a microscopic semiconductor-based component that forms the basic building block of photodetector arrays, such as those in CMOS or CCD image sensors. Each pixel consists of a photodiode or phototransistor that absorbs incident photons and generates a corresponding electrical charge or current. This component is critical for capturing light intensity and color information in digital imaging systems, with performance parameters including quantum efficiency, dark current, and dynamic range.

The photosensitive pixel operates on the photoelectric effect, where incident photons strike a semiconductor material (e.g., silicon), creating electron-hole pairs. In a photodiode-based pixel, this generates a photocurrent proportional to light intensity. In CMOS pixels, the charge is typically integrated in a capacitor and read out via on-chip amplifiers, while CCD pixels transfer charge through adjacent pixels to a readout node. Key processes include photon absorption, charge generation, charge collection, and signal conversion.