Three photodiodes D1, D2 and D3 are made of semiconductors having band gaps of 2.5eV, 2eV and 3eV, respectively. Which ones will be able to detect light of wavelength 6000 Ao?
Energy of incident light photon, E=hν=λhc =6×10−7×1.6×10−196.6×10−34×3×108=2.06eV For the incident radiation to be detected by the photodiode , energy of incident radiation photon should be greater than the band gap. This is true only for D2. Therefore , only D2 will detect this radiation.
