Book contents
- Frontmatter
- Contents
- On Seeing the Light
- Introduction
- 1 Simple Models of the Electron–Phonon Interaction
- 2 Quantum Confinement of Carriers
- 3 Quasi-Continuum Theory of Lattice Vibrations
- 4 Bulk Vibrational Modes in an Isotropic Continuum
- 5 Optical Modes in a Quantum Well
- 6 Superlattice Modes
- 7 Optical Modes in Various Structures
- 8 Electron–Optical Phonon Interaction in a Quantum Well
- 9 Other Scattering Mechanisms
- 10 Quantum Screening
- 11 The Electron Distribution Function
- Appendix: The Polar-Optical Momentum-Relaxation Time in a 2D Degenerate Gas
- References
- Index
7 - Optical Modes in Various Structures
Published online by Cambridge University Press: 16 February 2010
- Frontmatter
- Contents
- On Seeing the Light
- Introduction
- 1 Simple Models of the Electron–Phonon Interaction
- 2 Quantum Confinement of Carriers
- 3 Quasi-Continuum Theory of Lattice Vibrations
- 4 Bulk Vibrational Modes in an Isotropic Continuum
- 5 Optical Modes in a Quantum Well
- 6 Superlattice Modes
- 7 Optical Modes in Various Structures
- 8 Electron–Optical Phonon Interaction in a Quantum Well
- 9 Other Scattering Mechanisms
- 10 Quantum Screening
- 11 The Electron Distribution Function
- Appendix: The Polar-Optical Momentum-Relaxation Time in a 2D Degenerate Gas
- References
- Index
Summary
It cannot be thus long, the sides of nature will not sustain it.
Antony and Cleopatra, W. ShakespeareIntroduction
This chapter deals with several topics. There is considerable interest in fabricating quasi-2D structures in which the electron–phonon interaction is reduced. Optical-phonon engineering is in its infancy, but already there have been investigations of the effect of incorporating monolayers and conducting layers. One of the first quasi-2D systems to be studied was the thin ionic slab, yet there are still problems connected with the description of optical modes in such structures. The increasing sophistication of microfabrication techniques has led to the creation of quasi-one-dimensional (quantum wires) and quasi-zero-dimensional (quantum dots) structures that are expected to have interesting physical properties. It is important to establish the mode structure, both electron and vibrational, in these systems. In this chapter we consider some of these topics briefly.
Monolayers
The study of short-period superlattices in electronic and optical devices has received considerable attention and there are several reasons why this has been so. Ease of growth and reduction of interface roughness and residual impurities make for more perfect structures. Replacing random alloys, such as AlxGa1 – x As, with their ordered superlattice counterparts (GaAs)m/(AlAs)n eliminates alloy scattering. In the AlxGa1–x As system there is the added advantage of avoiding the troublesome DX center. The replacement of random alloys by equivalent superlattices in bandgap engineering is unproblematic.
- Type
- Chapter
- Information
- Electrons and Phonons in Semiconductor Multilayers , pp. 161 - 183Publisher: Cambridge University PressPrint publication year: 1996