photovoltaic detector

photovoltaic detector

(foh-toh-vol-tay -ik) An electronic device designed to detect photons of electromagnetic radiation. It consists of a junction between two opposite-polarity semiconductors (a p-n junction). Photons absorbed at or near the junction cause the emission of charge carriers that are separated by the junction to produce an external voltage. The magnitude of the voltage is related to the number of incident photons. This type of instrument is used in astronomy to detect ultraviolet and infrared radiation; for example, an indium antimonide (InSb) detector is used in the near-infrared (see infrared detectors). To achieve optimum performance in the infrared the detectors are cooled, for example by liquid nitrogen to operate at 77 K or with liquid helium to function at about 4 K. In contrast to bolometers, photovoltaic detectors exhibit no significant temperature change in their responsive elements.