Book contents
- Frontmatter
- Contents
- Preface
- Chapter 1 Basic Concepts in Quantum Mechanics
- Chapter 2 One-Dimensional Potential Problems
- Chapter 3 Three-Dimensional Problems
- Chapter 4 Approximation Methods in Quantum Mechanics
- Chapter 5 Equilibrium Statistical Mechanics
- Chapter 6 Nonequilibrium statistical Mechanics
- Chapter 7 Multielectron Systems and Crystalline Symmetries
- Chapter 8 Motion of Electrons in a Periodic Potential
- Chapter 9 Phonons and Scattering Mechanisms in Solids
- Chapter 10 Generation and Recombination Processes In Semiconductors
- Chapter 11 Junctions
- Chapter 12 Semiconductor Photonic Detectors
- Chapter 13 Optoelectronic Emitters
- Chapter 14 Field-Effect Devices
- References
- Index
Chapter 9 - Phonons and Scattering Mechanisms in Solids
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- Chapter 1 Basic Concepts in Quantum Mechanics
- Chapter 2 One-Dimensional Potential Problems
- Chapter 3 Three-Dimensional Problems
- Chapter 4 Approximation Methods in Quantum Mechanics
- Chapter 5 Equilibrium Statistical Mechanics
- Chapter 6 Nonequilibrium statistical Mechanics
- Chapter 7 Multielectron Systems and Crystalline Symmetries
- Chapter 8 Motion of Electrons in a Periodic Potential
- Chapter 9 Phonons and Scattering Mechanisms in Solids
- Chapter 10 Generation and Recombination Processes In Semiconductors
- Chapter 11 Junctions
- Chapter 12 Semiconductor Photonic Detectors
- Chapter 13 Optoelectronic Emitters
- Chapter 14 Field-Effect Devices
- References
- Index
Summary
In this chapter, we consider what happens when the lattice is no longer in equilibrium. In Chapter 8 we considered the motion of electrons in a crystal assuming that the ions were at rest for all times about their equilibrium positions. The presence of the ionic potential on the electrons results in energy-band formation: allowed ranges of energies for the electrons. However, this is not a physically realistic situation, since at nonzero lattice temperatures, the ions undergo some oscillation about their equilibrium positions. This additional motion, called lattice vibration, has important consequences on the behavior of the electrons. In Section 9.1 we consider lattice vibrations and the quanta of lattice vibrations, phonons. In the subsequent sections, we then examine how phonons influence the electronic properties of a crystal.
Lattice Vibrations and Phonons
From the discussion in Chapter 7, we found that the equilibrium configuration of the ions results in the minimum potential energy of the crystal. As the ions become more compressed, a repulsive force due to the nuclear-nuclear interaction acts to restore the system back to equilibrium. Similarly, as the lattice is stretched, the attractive force from the molecular bonds formed between adjacent ions acts again to restore equilibrium. Hence a lattice can be thought of as a collection of mass centers situated at definite positions and held together by the action of an elastic restoring force. The system has a definite minimum potential energy.
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- Information
- The Physics of SemiconductorsWith Applications to Optoelectronic Devices, pp. 453 - 488Publisher: Cambridge University PressPrint publication year: 1999