Question

Explain:

(i) Three Photo diodes D₁, D₂ and D₃ are made of semiconductor having band gaps of 2.5 eV, 2 eV, and 3 eV respectively. Which one be able to detech light of wavelength 600 Å?

(ii) Why b an elemental semiconductor cannot be used to make visible LEDs?

Answer 1

(ii) Number of Free electrons are very small leading to negligible conduction.