Special Purpose Diodes
Which of the following statement is NOT correct in the case of LED?
(A) It is a heavily doped p-n junction diode.
(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.
Show answer and solution
Answer: (c)
- (A) True: an LED is a heavily doped p-n junction.
- (B) True: light comes from recombination, which happens only in forward bias.
- (C) False: in reverse bias there is no recombination, so no light.
- (D) True: photon energy .
- So the answer is (c) C.