Suppose the energy liberated in the recombination of a hole-electron pair is converted into electromagnetic radiation. If the maximum wavelength emitted is 820 nm, what is the band gap?
Minimum energy will produce maximum wavelength and ∴ we consider the energy lost by the electrons is only due to it moving from the conduction to valence band, which is the energy band gap
The energy lost is in the form of electromagnetic radiation, for which the energy is given as following,
where,
,
is the wavelength
∴
∴ Energy band gap = 1.514eV
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