Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 18: Problem 27

(a) Explain why no hole is generated by the electron excitation involving a donor impurity atom. (b) Explain why no free electron is generated by the electron excitation involving an acceptor impurity atom.

Short Answer

Expert verified
Answer: No hole is generated during the electron excitation process involved with a donor impurity atom because the excitation process does not leave a vacancy in the valence band; instead, the donor site stays positively charged. No free electron is generated during the electron excitation process involved with an acceptor impurity atom because the electron is not excited to the conduction band; instead, the electron fills a vacancy in the valence band created by the acceptor impurity, and the acceptor site becomes negatively charged.

Step by step solution

01

Understand the Impurity Atoms

Donor impurity atoms are atoms that have an extra valence electron compared to the atoms of a semiconductor crystal. They can donate this extra electron to the crystal lattice. Acceptor impurity atoms, on the other hand, have one less valence electron and can accept an electron from the semiconductor crystal.
02

Analyze Donor Impurity Atoms and Electron Excitation

In the case of a donor impurity atom, it donates an extra electron to the conduction band. When the electron is excited from the donor impurity level to the conduction band, there is no vacancy created in the valance band. Instead, the donor site is left positively charged because it has lost an electron, but no hole is created in the valence band.
03

Answer for Part (a)

Therefore, for part (a) of the exercise, no hole is generated by the electron excitation involving a donor impurity atom because the excitation process does not leave a vacancy in the valence band. Instead, the donor site stays positively charged.
04

Analyze Acceptor Impurity Atoms and Electron Excitation

In the case of an acceptor impurity atom, it accepts an electron from the valence band to complete its outer electron shell. This process creates a hole in the valence band. When an electron from the valence band fills the hole created, the acceptor site becomes negatively charged.
05

Answer for Part (b)

For part (b) of the exercise, no free electron is generated by the electron excitation involving an acceptor impurity atom because the electron is not excited to the conduction band. Instead, the electron fills a vacancy in the valence band created by the acceptor impurity, and the acceptor site becomes negatively charged.

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

In terms of electron energy band structure, discuss reasons for the difference in electrical conductivity between metals, semiconductors, and insulators.

(a) Using the data in Table \(18.1\), compute the resistance of a copper wire \(3 \mathrm{~mm}(0.12\) in.) in diameter and \(2 \mathrm{~m}(78.7 \mathrm{in}\).) long. (b) What would be the current flow if the potential drop across the ends of the wire is \(0.05 \mathrm{~V}\) ? (c) What is the current density? (d) What is the magnitude of the electric field across the ends of the wire?

(a) Using the data presented in Figure 18.16, determine the number of free electrons per atom for intrinsic germanium and silicon at room temperature \((298 \mathrm{~K})\). The densities for Ge and \(\mathrm{Si}\) are \(5.32\) and \(2.33 \mathrm{~g} / \mathrm{cm}^{3}\), respectively. (b) Now explain the difference in these freeelectron-per-atom values.

Briefly describe electron and hole motions in a \(p-n\) junction for forward and reverse biases; then explain how these lead to rectification.

Estimate the temperature at which GaAs has an electrical conductivity of \(3.7 \times 10^{-3}\) \((\Omega \cdot \mathrm{m})^{-1}\), assuming the temperature dependence for \(\sigma\) of Equation 18.36. The data shown in Table \(18.3\) may prove helpful.
See all solutions

Recommended explanations on Physics Textbooks

Fundamentals of Physics

Read Explanation

Kinematics Physics

Read Explanation

Classical Mechanics

Read Explanation

Electromagnetism

Read Explanation

Modern Physics

Read Explanation

Space Physics

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