Dark current (physics)

<p>In <a href="/facts/Physics/a7aH2y08">physics</a> and in <a href="/facts/Electronic_engineering/WCSVulpu">electronic engineering</a>, dark current is the relatively small <a href="/facts/Electric_current/Dc1xdnUX">electric current</a> that flows through <a href="/facts/Photodetector/7cSkXS6s">photosensitive devices</a> such as a <a href="/facts/Photomultiplier_tube/bjbB9fBE">photomultiplier tube</a>, <a href="/facts/Photodiode/152Rpk06">photodiode</a>, or <a href="/facts/Charge-coupled_device/l6xffIcz">charge-coupled device</a> even when no <a href="/facts/Photon/mFNhAEzA">photons</a> enter the device; it consists of the charges generated in the detector when no outside radiation is entering the detector. It is referred to as <a href="/facts/Reverse_bias/CaKIdLPg">reverse bias</a> <a href="/facts/Leakage_current/Nd6PNxhV">leakage current</a> in non-optical devices and is present in all <a href="/facts/Diode/JyaoyGnk">diodes</a>. Physically, dark current is due to the random generation of <a href="/facts/Electron/L0KBo5cW">electrons</a> and <a href="/facts/Electron_hole/YymdTv9d">holes</a> within the <a href="/facts/Depletion_region/54fB1pfE">depletion region</a> of the device.
</p><p>Dark current is one of the main sources for noise in <a href="/facts/Image_sensor/j3GNrRln">image sensors</a> such as charge-coupled devices. The pattern of different dark currents can result in a <a href="/facts/Fixed-pattern_noise/Ir0C9CLz">fixed-pattern noise</a>; <a href="/facts/Dark_frame_subtraction/pqQ7KtzN">dark frame subtraction</a> can remove an estimate of the mean fixed pattern, but there still remains a temporal noise, because the dark current itself has a <a href="/facts/Shot_noise/Vblzt9ux">shot noise</a>.
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Dark current (physics) open-in-new

Dark current (physics)