The electric field profile in the depletion region of a PN junction in equilibrium is shown below. Which one of the following statement is TRUE ?

Explanation:

The electric field profile in the depletion region of a PN junction in equilibrium is a critical aspect of understanding the behavior of semiconductor devices. Let's delve into the correct option and analyze the other options to provide a comprehensive solution.

Depletion Region of a PN Junction:

In a PN junction, the depletion region is formed when P-type and N-type semiconductors are joined together. The P-type semiconductor has an abundance of holes (positive charge carriers), while the N-type semiconductor has an abundance of electrons (negative charge carriers). When these two types are brought into contact, electrons from the N-side diffuse into the P-side and recombine with holes, and holes from the P-side diffuse into the N-side and recombine with electrons. This diffusion process creates a region devoid of free charge carriers, known as the depletion region.

The electric field in the depletion region is established due to the fixed ionized donor atoms (positive ions) on the N-side and acceptor atoms (negative ions) on the P-side. The electric field direction is from the N-side to the P-side, and it opposes the diffusion of charge carriers, thus establishing equilibrium.

Correct Option Analysis:

The correct option is:

Option 1: The left side of the junction is P-type and the right side is N-type.

This option is correct because the electric field direction in the depletion region of a PN junction at equilibrium is from the N-type to the P-type region. This indicates that the left side (where the electric field originates) is P-type, and the right side (where the electric field terminates) is N-type. The electric field profile typically shows a peak near the junction and decreases as we move away from the junction on both sides.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 2: Both the N-type and P-type depletion regions are non-uniformly doped.

This option is incorrect. While it is possible to have non-uniform doping in some advanced semiconductor devices, a standard PN junction in equilibrium typically assumes uniform doping concentrations for simplicity. Non-uniform doping would complicate the electric field profile, but it does not inherently define the nature of the depletion region in equilibrium.

Option 3: If the P-type has a doping concentration of 10¹⁰ cm⁻³, then the doping concentration in the N-type region will be 10¹¹ cm⁻³.

This option is also incorrect. The relationship between the doping concentrations of the P-type and N-type regions does not follow a fixed ratio like 10¹⁰ cm⁻³ to 10¹¹ cm⁻³. The doping concentrations are typically chosen based on the desired electrical properties of the PN junction, and they can vary widely depending on the application. The given concentrations are arbitrary and do not reflect a universal rule.

Option 4: None of the options.

This option is incorrect because Option 1 is indeed correct. Therefore, stating that none of the options are correct would be inaccurate.

Conclusion:

Understanding the electric field profile in the depletion region of a PN junction is crucial for analyzing semiconductor devices. In equilibrium, the electric field direction is from the N-type region to the P-type region, confirming that the left side is P-type and the right side is N-type. This understanding helps in designing and optimizing various semiconductor components such as diodes, transistors, and integrated circuits. The analysis of other options further reinforces the correctness of Option 1, highlighting the importance of accurate doping concentration and uniformity in semiconductor physics.