Q. A p-n photodiode is made of a material with a band gap of 2.0 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly
A) 20 × 10¹⁴ Hz
B) 10 × 10¹⁴ Hz
C) 5 × 10¹⁴ Hz
D) 1 × 10¹⁴ Hz
Explanation
[Solution from source] The photon must at least bridge the band gap: ν = Eg/h = (2.0 × 1.6 × 10⁻¹⁹)/(6.63 × 10⁻³⁴) ≈ 4.8 × 10¹⁴ Hz ≈ 5 × 10¹⁴ Hz. 10 × 10¹⁴ Hz would correspond to a 4 eV gap. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.