Question

If a semiconductor photodiode can detect a photon with a maximum wavelength of 400 nm, then its band gap energy is 

Planck’s constant h = 6.63 × 10^–34 J.s. 

Speed of light c = 3 × 10⁸ m/s 

(1) 1.1 eV 

(2) 2.0 eV 

(3) 3.1 eV 

(4) 1.5 eV

Answer 1

(3) 3.1 eV 

For photodiode to detect hc/ λ > band gap energy 

⇒ band gap energy max hc/λ_max