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Concepts Of Physics MCQ Edition [Volume 2]PhysicsSemiconductors and Semiconductor Devices

When exposed to light, the conductivity of a photodiode material increases. It is observed that this change in conductivity happens only for wavelengths less than 620 nm . Calculate the band gap.

Options

  1. A3 eV
  2. B4 eV
  3. C2 eV
  4. D1 eV

Correct answer

C. 2 eV

Step-by-step solution

The change in conductivity of a photodiode material occurs when the incident photon energy is greater than or equal to the band gap energy of the material. The threshold wavelength corresponds to the band gap energy E_g . The relation between band gap energy and threshold wavelength is given by E_g = hc Using the standard approximation hc 1240 eV nm , we get E_g = 1240 620 eV E_g = 2 eV

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