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The reverse-biased current of a particul...

The reverse-biased current of a particular p-n junction diode increases when it is expoesed to light of wavelength less than or equal to 600nm.Assume that the increases in carrier concentration takes place due to the creation of new hole-electron pairs by the light.Find the band gap.

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The reverse-biased current is caused mainly due to the drift current. The dirft current in a p-n junction is caused by the formation of new hole-electron pairs and their subsequent motions in the depletion layer. When the junction is exposed to light,it may absorb energy form the light photons. If this energy supplied by a photon is greater than (or equal to )the band gap,a hole-electorns pair may be formed. Thus, the reverse-biased current will invrease if the light Photons have energy gtrater than (or equal to )the band gap. hence the band gap is equal to the energy of a Photon of 600 nm light which is
`hc/(lambda)=1242eV nm/600 nm=2.07eV.`
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