Point Defects in Solids

Volume 1 of Point Defects in Solids has as its major emphasis defects in ionic solids. Volume 2 now extends this emphasis to semiconductors. The first four chapters treat in some detail the creation, kinetic behavior, inter­ actions, and physical properties of both simple and composite defects in a variety of semiconducting systems. Also included, as in Vol. 1, are chapters on special topics, namely phonon-defect interactions and defects in organic crystals. Defect behavior in semiconductors has been a subject of considerable interest since the discovery some twenty-five years ago that fast neutron irradiation profoundly affected the electrical characteristics of germanium and silicon. Present-day interest has been stimulated by such semiconductor applications as solar cell power plants for space stations and satellites and semiconductor particle and y-ray detectors, since in both radiation damage can cause serious deterioration. Of even greater practical concern is the need to understand particle damage in order to capitalize upon the develop­ ing technique of ion implantation as a means of device fabrication. Although the periodic international conferences on radiation effects in semiconductors have served the valuable function of summarizing the extensive work being done in this field, these proceedings are much too detailed and lack the background discussion needed to make them useful to the novice.

1. Defect Creation in Semiconductors.- 1. Introduction.- 2. Defect Properties.- 2.1. Introduction.- 2.2. Silicon.- 2.3. Germanium.- 2.4. Diamond.- 2.5. III–V Compounds.- 2.6. II–VI Compounds.- 2.7. Other Materials.- 3. Damage Phenomenology.- 3.1. Displacement Damage.- 3.2. Thermal Spikes.- 3.3. Ionization Phenomenology.- 3.4. Plastic Deformation.- 3.5. Heat Treatment Effects.- 4. Interactions of Particles with Semiconductors.- 4.1. Introduction.- 4.2. Photon Interactions.- 4.3. Heavy Ions and Atoms.- 4.4. Electrons.- 4.5. Neutrons.- 5. Survey of Displacement Damage Results.- 5.1. Introduction.- 5.2. Germanium.- 5.3. Silicon.- 5.4. Diamond and Graphite.- 5.5. III–V Compounds.- 5.5.1. InSb, InAs, InP.- 5.5.2. GaAs, GaSb.- 5.6. II–VI Compounds.- 5.6.1. ZnSe, ZnTe, ZnS.- 5.6.2. CdS, CdSe, CdTe.- 5.6.3. MgO, ZnO, BeO.- 6. Subthreshold and Ionization Damage.- 7. Theories of Displacement Damage Production.- 8. Summary.- References.- 2. Diffusion in Semiconductors.- 1. Introduction.- 2. Atomic Theory of Diffusion.- 2.1. Diffusion Mechanisms.- 2.2. The Flux Equation and Diffusivity.- 2.2.1. The Diffusive Flux.- 2.2.2. Jump Frequency.- 2.2.3. Diffusivity and Activation Energy.- 3. Continuum Theory of Diffusion.- 3.1. Fick’s Laws.- 3.2. The Diffusion Profile.- 3.3. Impurity Diffusion for a Moving Boundary.- 3.3.1. Experimental Conditions for a Moving Boundary.- 3.3.2. Diffusion into a Growing Layer.- 3.3.3. Diffusion into an Evaporating Surface.- 3.4. The Boltzmann—Matano Analysis.- 4. Diffusion in Ge and Si.- 4.1. Introduction.- 4.2. Self-Diffusion in Ge and Si.- 4.3. Diffusion of the Group III and V Impurities in Ge and Si.- 4.3.1. Low-Concentration Case.- 4.3.2. High-Concentration Case.- 4.4. Interstitial Diffusion of the Alkali Elements and Inert Gases.- 4.5. Interstitial-Substitutional Diffusion of the Transition Elements.- 4.5.1. Preliminary Considerations.- 4.5.2. Low Solubility and Slow Interstitial Diffusion.- 4.5.3. Intermediate Solubility and Rapid Interstitial Diffusion.- 4.5.4. High Solubility and Slow Interstitial Diffusion.- 4.6 Graphical Summary of the Diffusion Coefficients in Si.- 5. Diffusion in the III–V Compounds.- 5.1. Introduction.- 5.2. Ternary Considerations.- 5.3. Concentration Gradient Diffusion of Zn in GaAs.- 5.4. Interstitial-Substitutional Diffusion.- 5.4.1. The Flux Equation.- 5.4.2. The Built-in Field.- 5.4.3. The Effective Diffusion Coefficient.- 5.4.4. Interstitial—Substitutional Equilibrium.- 5.4.5. Analysis of Experimental Data.- 5.4.6. Isoconcentration Diffusion.- 5.5. Effects of Arsenic Pressure.- 5.6. Departure from Equilibrium.- 5.7. Compilation of Diffusion Coefficients in the III–V Compounds.- 6. Diffusion in the II–VI Compounds.- 6.1. Introduction.- 6.2. Solid-Liquid-Vapor Equilibrium.- 6.2.1. Component Partial Pressures.- 6.2.2. Congruent Evaporation and Minimum Pressure.- 6.2.3. The Solidus Curve.- 6.3. Self-Diffusion.- 6.3.1. General Comments.- 6.3.2. Effective Diffusion Coefficient.- 6.3.3. Self-Diffusion in CdS.- 6.3.4. Compilation of Self-Diffusion Coefficients in the II–VI Compounds.- 7. Summary and Conclusions.- References.- 3. Effects of Point Defects on Electrical and Optical Properties of Semiconductors.- 1. Introduction.- 2. Carrier Concentration.- 2.1. Germanium.- 2.1.1. Energy Levels.- 2.1.2. Thermal Annealing.- 2.1.3. Radiation-Induced Annealing.- 2.2. Silicon.- 2.2.1. Energy Levels.- 2.2.2. Temperature Dependence of Defect Introduction Rates.- 2.3. Compound Semiconductors.- 3. Carrier Mobility.- 3.1. Germanium.- 3.2. Silicon.- 3.3. Other Materials.- 4. Minority Carrier Lifetime.- 4.1. Two-Level Model for Recombination.- 4.2. Recombination in Irradiated Germanium.- 4.2.1. Moderate-Resistivity n-Type Material.- 4.2.2. Low-Resistivity n-Type Material.- 4.2.3. p-Type Material.- 4.3. Silicon.- 4.3.1. Analysis for n-Type Material with Two Levels Effective at Low Excess Density.- 4.3.2. p-Type Material.- 4.3.3. Annealing Studies.- 5. Optical Absorption.- 5.1. Germanium.- 5.2. Silicon.- 5.3. III–V Compound Semiconductors.- 6. Photoconductivity.- 6.1. Germanium.- 6.2. Silicon.- 6.3. Other Materials.- 7. Luminescence.- 7.1. Recombination Luminescence in Irradiated Silicon.- 7.2. Effects of Irradiation on Luminescence in Gallium Arsenide.- 8. Conclusion.- References.- 4. Electron Paramagnetic Resonance of Point Defects in Solids, with Emphasis on Semiconductors.- 1. Introduction.- 2. Basic Concepts.- 2.1. Origin of Paramagnetism.- 2.2. Diamagnetic Solids.- 2.3. Concept of Resonance.- 2.4. Experimental Apparatus.- 3. Theory of EPR for Defects in Solids.- 3.1. Quenching of Orbital Angular Momentum.- 3.2. Hyperfine Interactions.- 3.2.1. Changes in the Spectrum.- 3.2.2. Examples.- 3.2.3. Quantitative Aspects of the hf Interaction.- 3.2.4. ENDOR.- 3.3. The g-Tensor.- 3.3.1. Changes in the Spectrum.- 3.3.2. Quantitative Treatment of the g-Tensor.- 3.3.3. The g-Shift of the Vk Center.- 3.4. Fine Structure Terms for S > 1/2.- 3.4.1. Changes in Spectrum.- 3.4.2. Origin of D.- 3.4.3. Higher Order Terms for S > 3/2.- 3.5. Orbital Angular Momentum Not Quenched.- 3.6. Summary.- 4. Additional Examples.- 4.1. Defects in Irradiated Silicon.- 4.1.1. Annealing of Interstitial Aluminum.- 4.1.2. The Oxygen—Vacancy Pair.- 4.1.3. The Phosphorus—Vacancy Pair.- 4.1.4. Multiple-Vacancy Defects.- 4.2. Transition Elements in Silicon.- 5. Auxiliary Techniques.- 5.1. Applied Uniaxial Stress.- 5.1.1. Jahn–Teller Alignment.- 5.1.2. Defect Alignment.- 5.1.3. Correlation with Optical Dichroism.- 5.1.4. Electrical Level Determination.- 5.1.5. Removing Orbital Degeneracy.- 5.1.6. Distortion of the Wave Function.- 5.2. Applied Electric Fields.- 5.3. Optical Illumination in situ.- 5.3.1. Excited States.- 5.3.2. Metastable Charge States.- 5.3.3. Optical Alignment.- 5.4. Studies of the Effect of Temperature.- 5.4.1. Annealing.- 5.4.2. Linewidth.- 5.4.3. Relaxation Times.- 5.5. Defect Production.- 5.6. Optical Detection of EPR.- References.- 5. Phonon-Defect Interaction.- 1. Introduction.- 2. Theoretical Background.- 2.1. General.- 2.2. Multiple Scattering.- 2.2.1. The Coherent Potential Approximation (CPA).- 2.2.2. Range of Validity of CPA.- 2.2.3. Summary and Conclusion.- 3. External Interactions.- 3.1. Theory.- 3.1.1. Mass-Defect and Force Constant Changes.- 3.1.2. Strain-Field Scattering.- 3.2. Experiment.- 3.2.1. Mass-Defect Scattering—Isotopes.- 3.2.2. Scattering Due to Mass and Force Constant Changes.- 3.2.3. Strain Fields.- 4. Internal Interactions.- 4.1. Introduction.- 4.2. Theoretical Background.- 4.2.1. Partial Wave Analysis.- 4.2.2. Formal Scattering Theory.- 4.2.3. Form of the Interaction.- 4.2.4. Dispersion Relations.- 4.2.5. Scattering Cross Section.- 4.3. Paramagnetic Ions.- 4.3.1. Theory.- 4.3.2. Experiment.- 4.4. “Molecular” Defects.- 4.4.1. Experimental.- 4.4.2. Comparison with Experiment.- 4.4.3. Some Other Probable Consequences.- 5. Summary and Conclusion.- References.- 6. Point Defects in Molecular Solids.- 1. Introduction.- 2. Self-Diffusion.- 2.1. Radiotracer Measurements.- 2.1.1. Tracers.- 2.1.2. Specimen Preparation.- 2.1.3. Sectioning Experiments.- 2.1.4. Penetration Profiles.- 2.1.5. Integrating Techniques.- 2.1.6. Results.- 2.2. Nuclear Magnetic Resonance Measurements.- 2.3. Radical Recombination Studies.- 2.4. Summary.- 3. Experimental Determination of the Formation and Migration Parameters for Point Defects.- 3.1. Excess Specific Heat Studies.- 3.2. Thermal Expansivity Measurements.- 3.3. Compressibility Measurements.- 3.4. Summary.