Point Defects in Semiconductors II Experimental Aspects

In introductory solid-state physics texts we are introduced to the concept of a perfect crystalline solid with every atom in its proper place. This is a convenient first step in developing the concept of electronic band struc­ ture, and from it deducing the general electronic and optical properties of crystalline solids. However, for the student who does not proceed further, such an idealization can be grossly misleading. A perfect crystal does not exist. There are always defects. It was recognized very early in the study of solids that these defects often have a profound effect on the real physical properties of a solid. As a result, a major part of scientific research in solid-state physics has,' from the early studies of "color centers" in alkali halides to the present vigorous investigations of deep levels in semiconductors, been devoted to the study of defects. We now know that in actual fact, most of the interest­ ing and important properties of solids-electrical, optical, mechanical- are determined not so much by the properties of the perfect crystal as by its im­ perfections.

1. Introduction.- 2. Lattice Distortion and the Jahn-Teller Effect.- 2.1 The Electron-Phonon Interaction.- 2.2 Symmetry Considerations: The Stable Atomic Configurations.- 2.3 Coupled Electronic and Nuclear Motion: Vibronic States — Static and Dynamic Jahn-Teller Limits.- 2.4 The Vacancy in Silicon.- 3. Electron Paramagnetic Resonance.- 3.1 The Hamiltonian.- 3.2 Electronic Zeeman Interaction.- 3.3 Spin Orbit Coubling.- 3.4 Hyperfine Interaction.- 3.5 Nuclear Zeeman Interaction — Double Resonance.- 3.6 Spin-Spin Interaction. Fine Structure.- 3.7 EPR of Impurities and Vacancy — Impurity Pairs in Silicon.- 3.8 The Vacancy in Silicon.- 4. Optical Properties.- 4.1 Transition Probability.- 4.2 The Configuration Coordinate Diagram.- 4.3 Optical Line Shape and the Electron-Lattice Interaction.- 4.4 Optical Cross Section.- 4.5 An Example. The GR Absorption Band in Diamond.- 5. Electrical Properties.- 5.1 Carrier Distribution Between Bands and Defect Levels.- 5.2 Conduction in Case of Defect Interaction.- 5.3 Carrier Scattering.- 6. Carrier Emission and Recombination.- 6.1 Emission and Capture Rates.- 6.2 Experimental Observation of Emission Rates.- 6.3 Nonradiative Recombination Processes.- 6.4 Experimental Determination of Ionization Energies, Entropies and Cross Sections.- 6.5 Influence of the Electric Field on Emission Rates.- 7. Other Methods of Detection.- 7.1 Photoexcitation.- 7.2 Optical Detection of Paramagnetic Resonance.- 7.3 Direct Detection of Phonons.- 8. Defect Production by Irradiation.- 8.1 Interaction of Radiation with Solids.- 8.2 Defect Production.- 8.3 Defect Nature and Spatial Distribution.- 8.4 Experimental Determination of a Threshold Energy.- 8.5 Subthreshold Effects.- 9. Defect Annealing.- 9.1 Annealing Kinetics.- 9.2 Determination of the AnnealingParameters.- 9.3 Annealing of Defects Induced by Electron Irradiation.- References.