Question

Direction of the electric field in P-N junction diode is
A. From the P side to the N side
B. From the N side to the P side
C. Randomly oriented
D. The electric field does not exist

Answer 1

Hint: The junction is formed when the p-type or the n-type is doped with the n-type or the p-type respectively. The depletion region is formed between the p-type and n-type material due to which the electric field is developed. The direction of the electric field is from the positive charges to the negative charges.

Step by step solution:
What is PN junction ?
PN junction is the boundary formed between two semiconductor material namely P-type and n types are joined together

The P side of the semiconductor is called a positive side and has the majority of the Carriers as holes and the n side of the semiconductor is called the negative side and has the majority of Carriers as electrons.
Let us see the formation of the depletion region.

Formation of PN junction :
PN junction is formed using the method of doping.
Let us consider a thin p-type silicon sheet and if we add a small amount of impurity to this the p-type it will get converted into n-type silicon. So now we get one side of the semiconductor as P-type in another side of the semiconductor as n-type .

At the junction of these two types, the electrons on the n side try to flow into the P side and the holes on the p side flow into the n - side.

As a result, the atoms on the n side loses the electrons and becomes static cations at the junction and the atoms in the p side gain the electrons to become the static anions
We know that the anions are negatively charged and cations are positively charged.
Due to the formation of static charges on either side of the boundary, an electric field develops in the direction from the N side to the P side.

Now due to this electric field, the movement of majority carriers is stopped and hence the depletion region is formed .

So the electric field direction in the depletion region is from the n-type to the p side

Note: The mistake that one can make in this kind of question is that we may think that the n-type is negatively charged and the p-type is positively charged and hence may conclude that the direction of the electric field is from the positive p-type to the wrong n type. The direction is from the n-type to the p-type and hence the field stops the diffusion of majority carriers .