Question

The leakage current across a p-n junction is due to____
(A) Minority carriers
(B) Majority of carriers
(C) Junction capacitance
(D) None of these

Answer 1

Hint:- A p-n junction is a boundary between a p-type and n-type semiconductor materials. In forward biased mode, p-n junction diode produces a forward current which is due to the majority charge carriers, and in reverse biasing, p-n junction diode produces a leakage current which is due to minority charge carriers.

Complete step by step solution:
Due to thermal energy, the pairs of electrons and holes are created continuously. This means few minority carriers exist on both sides of the junction. Many of them recombine with majority carriers but some may exit the depletion layer and reach the junction. When this happens, a small amount of current flows through an external circuit. This is called leakage current. Leakage current doesn't depend upon Voltage applied but increases considerably with an increase in temperature.
So, we can say that minority carriers are responsible for leakage current.

The correct option is (A).

Note: Let us understand the other options too:
Majority carriers: When a semiconductor is doped with an impurity, its conductivity increases due to an increase in free electrons or holes depending upon impurity. If the impurity added has 5 valence electrons, then each atom of impurity will have 1 free electron. These electrons are called majority carriers. If the impurity has 3 free electrons, then the majority of carriers will be the holes.

Junction capacitance: When a p-n junction diode is reverse biased, the depletion layer increases and majority carriers are pushed away from the junction, leaving behind more charged ions. This situation is like a capacitor having a charge on it. This phenomenon is called junction capacitance.