Which of the following statement is not correct in the case of light emitting diodes?
A. It is a heavily doped p-n junction.
B. It emits light only when it is forward biased.
C. It emits light only when it is reverse biased.
D. The energy of the light emitted is equal to or slightly less than the energy gap of the semiconductor used.
Choose the correct answer from the options given below:

We analyze each statement about Light Emitting Diodes (LEDs):

Statement A: "It is a heavily doped p-n junction." — This is correct. LEDs are made from heavily doped p-n junctions to ensure efficient radiative recombination of electrons and holes.

Statement B: "It emits light only when it is forward biased." — This is correct. Under forward bias, electrons and holes recombine at the junction, releasing energy as photons.

Statement C: "It emits light only when it is reverse biased." — This is incorrect. LEDs emit light under forward bias, not reverse bias. Under reverse bias, there is no significant recombination of charge carriers at the junction.

Statement D: "The energy of the light emitted is equal to or slightly less than the energy gap of the semiconductor used." — This is correct. The photon energy $$h\nu$$ is approximately equal to the band gap $$E_g$$, and can be slightly less due to thermal effects and other energy loss mechanisms.

The only incorrect statement is C.

The correct answer is Option C: C.