Photons conductivity changes resulting from absorption

The Conductivity Change That Results from Absorption of a Photon... 

Photovoltaic and photoconductive effects result from direct conversion of incident photons into conducting electrons within a material. The two effects differ in the method of sensing the photoexcited electrons electrically. Detectors based on these effects are called photon detectors, because they convert photons directly into conducting electrons no intermediate process is involved, such as the heating of the material by absorption of photons in a thermal detector which causes a change of a measurable electrical property. 

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