Which one of the following statement is true for a semiconductor p-n junction with no external bias?a)The total charge in the junction is not conserved.b)The p-side of the junction is positively charged.c)Then n-side of the junction is positively charged.d)No charge develops anywhere in the junction.Correct answer is option 'C'. Can you explain this answer?

Question

Answer

Explanation:

P-N Junction: A p-n junction is formed by joining a p-type semiconductor and an n-type semiconductor. The p-type region has an excess of holes (positive charge carriers), while the n-type region has an excess of electrons (negative charge carriers). When these two regions are brought into contact, diffusion of charge carriers occurs across the junction, resulting in the formation of a depletion region.

No external bias: When there is no external bias applied to the p-n junction, it is in thermal equilibrium. This means that the drift current and diffusion current are balanced, and there is no net flow of charge carriers across the junction.

Charge distribution in the junction: In the absence of an external bias, the charge distribution in the p-n junction can be explained as follows:

1. N-side: The n-side of the junction contains excess electrons due to the presence of the n-type semiconductor. These excess electrons create a negative charge on the n-side.

2. P-side: The p-side of the junction contains excess holes due to the presence of the p-type semiconductor. These excess holes create a positive charge on the p-side.

3. Depletion region: The region around the junction where there is a lack of charge carriers is called the depletion region. This region is formed due to the diffusion of charge carriers from the n-side to the p-side and vice versa. The depletion region acts as a barrier to the flow of current.

True statement: In the given options, the true statement is option 'C', which states that the n-side of the junction is positively charged. This is because the n-side has an excess of electrons, which creates a negative charge. In the absence of an external bias, the positive charge on the p-side and the negative charge on the n-side balance each other, resulting in no net charge in the junction.

Summary:
In a semiconductor p-n junction with no external bias, the n-side of the junction is positively charged. This is due to the excess of electrons present in the n-type semiconductor, which creates a negative charge. The positive charge on the p-side and the negative charge on the n-side balance each other, resulting in no net charge in the junction.

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