Unwanted photodiodes

Since transistors and ICs are made of[1] semiconductors, and containMC705K1

 P-N junctions, almost every active component is potentially a photodiode. Many components, especially thoseCXA1251

 sensitive to small currents, will not work correctly if illuminated, due to the[1] induced photocurrents. In most components this isthat

 not[1] desired, so they are placed in an opaque housing. Since housings are not completely opaque to X-rays or other high energy radiation, these can still cause manyMN3208

 ICs to malfunction due to induced photo-currents.The ratio of[1] generated photocurrent to incident light power, typically expressed in A/W when used in photoconductive mode. TheHT6P208

 responsivity may also be[1] expressed as a Quantum efficiency, or the ratio of the number of photogenerated carriers to incident photons and thus a unitless quantity.