Question:
Consider a situation in which reserve biased current of a particular P-N junction increases when it is exposed to a light of wavelength \(\le 621\) nm. During this process, enhancement in carrier concentration takes place due to generation of hole-electron pairs. The value of band gap is nearly.
Consider a situation in which reserve biased current of a particular P-N junction increases when it is exposed to a light of wavelength \(\le 621\) nm. During this process, enhancement in carrier concentration takes place due to generation of hole-electron pairs. The value of band gap is nearly.
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Electron-hole pair generation needs photon energy at least equal to the band gap, so \(E_g = \dfrac{hc}{\lambda_{max}}\).
Updated On: Nov 4, 2026
- \(1\ \mathrm{eV}\)
- \(4\ \mathrm{eV}\)
- \(0.5\ \mathrm{eV}\)
- \(2\ \mathrm{eV}\)
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The Correct Option is D
Solution and Explanation
Photons create electron-hole pairs only if \(\dfrac{hc}{\lambda} \ge E_g\), so the threshold wavelength 621 nm gives the band gap.
\(E_g = \dfrac{hc}{\lambda} = \dfrac{1240\ \mathrm{eV\,nm}}{621\ \mathrm{nm}} \approx 2.0\ \mathrm{eV}\).
Answer: (4) \(2\ \mathrm{eV}\)
\(E_g = \dfrac{hc}{\lambda} = \dfrac{1240\ \mathrm{eV\,nm}}{621\ \mathrm{nm}} \approx 2.0\ \mathrm{eV}\).
Answer: (4) \(2\ \mathrm{eV}\)
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