Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 10: Problem 66

Explain how a p–n junction makes an excellent rectifier

Short Answer

Expert verified
A p-n junction diode acts as an excellent rectifier because it allows current flow during the forward bias condition when a positive voltage is applied to the p-side and a negative voltage to the n-side, and blocks current flow during the reverse bias condition when a positive voltage is applied to the n-side and a negative voltage to the p-side. In this way, when an alternating current is applied to the p-n junction diode, the positive half cycle is conducted while the negative half cycle is blocked, effectively converting alternating current to direct current.

Step by step solution

01

Understand n-type and p-type semiconductors

An n-type semiconductor has an excess of electrons, also known as majority carriers, while a p-type semiconductor has an excess of holes, which are the majority carriers. The p-n junction diode can be visualized by joining the p-type and n-type semiconductors together. When these two types of semiconductors are brought into contact, electrons near the junction in the n-region recombine with holes near the junction in the p-region, forming a region known as the depletion region.
02

Depletion region and built-in potential

The depletion region is an insulating layer formed at the junction due to this recombination process. It consists of immobile positive and negative ions near the junction. These immobile ions create an electric field that opposes the flow of majority charge carriers, i.e., electrons from the n-region to the p-region and holes from the p-region to the n-region. The potential difference created by this electric field is called the built-in potential.
03

Forward bias condition

When a positive voltage is applied to the p-side of the diode and a negative voltage to the n-side, the diode is said to be in forward bias. The applied voltage reduces the potential barrier height across the depletion region, and an electric field is created in the same direction as the built-in potential field. Due to this, the majority charge carriers easily flow across the junction, and the diode conducts current in the forward direction.
04

Reverse bias condition

When a positive voltage is applied to the n-side and a negative voltage to the p-side, the diode is in reverse bias. In this case, the applied voltage increases the potential barrier across the depletion region, widening the insulating layer and further opposing the flow of majority carriers across the junction. As a result, the diode does not conduct current in the reverse direction (due to negligible minority carrier flow).
05

Rectification process

A p-n junction diode under forward bias condition allows the current to flow, and under reverse bias condition, it blocks the current flow. So, when an alternating current is applied, during the positive half cycle, the diode is in forward bias and conducts current, whereas in the negative half cycle, it is in reverse bias and does not conduct current. Therefore, the p-n junction diode allows current flow mostly in one direction while blocking it in the other, essentially converting alternating current to direct current, and acting as an excellent rectifier.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Pyrolusite is a mineral containing manganese ions and oxide ions. Its structure can best be described as a body-centered cubic array of manganese ions with two oxide ions inside the unit cell and two oxide ions each on two faces of the cubic unit cell. What is the charge on the manganese ions in pyrolusite?

Iron has a density of 7.86 \(\mathrm{g} / \mathrm{cm}^{3}\) and crystallizes in a body-centered cubic lattice. Show that only 68\(\%\) of a body-centered lattice is actually occupied by atoms, and determine the atomic radius of iron.

You have three covalent compounds with three very different boiling points. All of the compounds have similar molar mass and relative shape. Explain how these three compounds could have very different boiling points.

A metallic solid with atoms in a face-centered cubic unit cell with an edge length of 392 \(\mathrm{pm}\) has a density of 21.45 $\mathrm{g} / \mathrm{cm}^{3} .$ Calculate the atomic mass and the atomic radius of the metal. Identify the metal.

A plot of \(\ln \left(P_{\text { vap }}\right)\) versus 1\(/ T(\mathrm{K})\) is linear with a negative slope. Why is this the case?
See all solutions

Recommended explanations on Chemistry Textbooks

Ionic and Molecular Compounds

Read Explanation

Inorganic Chemistry

Read Explanation

Chemistry Branches

Read Explanation

Organic Chemistry

Read Explanation

Physical Chemistry

Read Explanation

Nuclear Chemistry

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free