Point Defects in Semiconductors and Insulators

This book introduces the principles and techniques of modern electron paramagnetic resonance (EPR) spectroscopy that are essential for applications used to determine microscopic defect structures. Many different magnetic resonance methods are required for investigating the microscopic and electronic properties of solids and uncovering correlations between those properties. In addition to EPR such methods include electron nuclear double resonance (ENDOR), electronically and optically detected EPR (the latter is known as ODENDOR), and electronically and optically detected ENDOR. This book comprehensively discusses experimental, technological, and theoretical aspects of these techniques from a practical point of view with many illustrative examples taken from semiconductors and insulators. The non-specialist is informed about the potential of the different methods. A researcher finds practical help in the application of commercial apparatus as well as useful guidance from ab initio theory for the task of deriving structure models from experimental data.

Texte du rabat

The precedent book with the title "Structural Analysis of Point Defects in Solids: An introduction to multiple magnetic resonance spectroscopy" ap­ peared about 10 years ago. Since then a very active development has oc­ curred both with respect to the experimental methods and the theoretical interpretation of the experimental results. It would therefore not have been sufficient to simply publish a second edition of the precedent book with cor­ rections and a few additions. Furthermore the application of the multiple magnetic resonance methods has more and more shifted towards materials science and represents one of the important methods of materials analysis. Multiple magnetic resonances are used less now for "fundamental" studies in solid state physics. Therefore a more "pedestrian" access to the meth­ ods is called for to help the materials scientist to use them or to appreciate results obtained by using these methods. We have kept the two introduc­ tory chapters on conventional electron paramagnetic resonance (EPR) of the precedent book which are the base for the multiple resonance methods. The chapter on optical detection of EPR (ODEPR) was supplemented by sections on the structural information one can get from "forbidden" transitions as well as on spatial correlations between defects in the so-called "cross relaxation spectroscopy". High-field ODEPR/ENDOR was also added. The chapter on stationary electron nuclear double resonance (ENDOR) was supplemented by the method of stochastic END OR developed a few years ago in Paderborn which is now also commercially available.

Contenu

1. Introduction.- 1.1 Structure of Point Defects.- 1.2 Basic Concepts of Defect Structure Determination by EPR.- 1.3 Superhyperfine and Electronic Structures of Defects in Solids.- 2. Fundamentals of Electron Paramagnetic Resonance.- 2.1 Magnetic Properties of Electrons and Nuclei.- 2.2 Electrons and Nuclei in an External Magnetic Field.- 2.3 Some Useful Relations for Angular Momentum Operators.- 2.4 Time Dependence of Angular Momentum Operators and Macroscopic Magnetization.- 2.5 Basic Magnetic Resonance Experiment.- 2.6 Spin-Lattice Relaxation.- 2.7 Rate Equations for a Two-Level System.- 2.8 Bloch Equations.- 2.9 Conventional Detection of Electron Paramagnetic Resonance and its Sensitivity.- 3. Electron Paramagnetic Resonance Spectra.- 3.1 Spin Hamiltonian.- 3.2 Electron Zeeman Interaction.- 3.3 g-Factor Splitting of EPR Spectra.- 3.4 Fine-Structure Splitting of EPR Spectra.- 3.5 Hyperfine Splitting of EPR Spectra.- 3.6 Superhyperfine Splitting of EPR Spectra.- 3.7 Inhomogeneous Line Widths of EPR Lines.- 4. Optical Detection of Electron Paramagnetic Resonance.- 4.1 Optical Transitions of Defects in Solids.- 4.2 Spectral Form of Optical Transitions of Defects in Solids.- 4.3 EPR Detected with Magnetic Circular Dichroism of Absorption Method.- 4.4 MCDA Excitation Spectra of ODEPR Lines (MCDA "Tagged" by EPR).- 4.5 Spatially Resolved MCDA and ODEPR Spectra.- 4.6 Measurement of Spin-Lattice Relaxation Time T1with MCDA Method.- 4.7 Determination of Spin State with MCDA Method.- 4.8 EPR of Ground and Excited States Detected with Optical Pumping.- 4.9 EPR Optically Detected in Donor-Acceptor Pair Recombination Luminescence.- 4.10 Optically Detected EPR of Triplet States.- 4.11 ODEPR of Trapped Excitons with MCDA Method.- 4.12 Sensitivity of ODEPR Measurements.- 4.13 Structural Information from Forbidden Transitions in MCDA-EPR Spectra.- 4.14 Spatial Correlation Between Defects by Cross-Relaxation-Spectroscopy.- 4.15 High-Field ODEPR/ODENDOR.- 5. Electron Nuclear Double Resonance.- 5.1 The Resolution Problem, a Simple Model.- 5.2 Type of Information from EPR and NMR Spectra.- 5.3 Indirect Detection of NMR, Double Resonance.- 5.4 Examples of ENDOR Spectra.- 5.5 Relations Between EPR and ENDOR Spectra, ENDOR-Induced EPR.- 5.6 Electron Nuclear Nuclear Triple Resonance (Double ENDOR).- 5.7 Temperature Dependence and Photo-Excitation of ENDOR Spectra.- 5.7.1 Temperature Dependence of ENDOR Spectra.- 5.7.2 Photo-Excitation of ENDOR Spectra.- 5.8 Stochastic ENDOR.- 6. Analysis of ENDOR Spectra.- 6.1 Qualitative Analysis of ENDOR Spectra.- 6.1.1 Spin Hamiltonian.- 6.1.2 Simple First Order Solution.- 6.1.3 Assignment of Nuclei.- 6.1.4 Angular Dependence of ENDOR Lines.- 6.1.5 Symmetry Considerations, Neighbor Shells.- 6.2 Quantitative Analysis of ENDOR Spectra.- 6.2.1 Higher Order Approximations.- 6.2.2 Large Anisotropic Hyperfine Interactions.- 6.2.3 Approximation with the Effective Electron Spin Seff.- 6.2.4 Second Order Splittings of the Superhyperfine Structure.- 6.2.5 Sample Alignment.- 6.2.6 Reconstruction of the EPR Line Shape from ENDOR Data.- 6.2.7 Asymmetric Superhyperfine Tensors.- 6.2.8 Selection Rules and ENDOR Line Intensities.- 6.2.9 ENDOR Spectra in the Case of a Large Quadrupole Interaction and Axial Symmetry.- 6.2.10 Powder ENDOR Spectra.- 6.2.11 Final Results Obtainable from the Analysis of ENDOR Spectra.- 7. Electrical Detection of Electron Paramagnetic Resonance.- 7.1 Experimental Methods to Detect EDEPR.- 7.2 Experimental Observation of EDEPR.- 7.3 The Donor-Acceptor Pair Recombination Model.- 7.4 On the Role of the Electron Irradiation for the Donor EPR in Silicon.- 7.5 Spatial Resolution and Low Frequency EDEPR.- 7.6 Electrical Detection of ENDOR.- 7.7 Concentration and Temperature Dependence of the EDEPR Signals.- 7.8 Further Spin-Dependent Recombination Models.- 7.8.1 The Lépine Model.- 7.8.2 The Model of Kaplan, Solomon and Mott.- 7.8.3 The Spin-Dependent SRH Model.- 8. Theoretical ab initio Calculations of Hyperfine Interactions.- 8.1 Electron States in Solids.- 8.1.1 Born-Oppenheimer Approximation.- 8.1.2 Hartree and Hartree-Fock Approximations.- 8.1.3 Density Functional Theory and Local Density Approximation.- 8.1.4 Computational Methods for Energy Band Calculations.- 8.2 Computational Methods for Deep Point Defects.- 8.2.1 Cluster Methods.- 8.2.2 The Supercell Method.- 8.2.3 Green's Function Methods.- 8.2.4 The Band Gap Problem and the Scissor Operator.- 8.3 Hyperfine Interactions.- 8.3.1 Non-relativistic Hyperfine Interactions.- 8.3.2 Scalar Relativistic Hyperfine Interactions.- 8.3.3 Magnetization Density for Many-Electron States.- 8.3.4 The Jahn-Teller Effect.- 8.3.5 The Core Polarization.- 8.3.6 Electrical Quadrupole Interaction.- 8.3.7 The Empirical LCAO Scheme.- 8.3.8 The Envelope Function Method.- 8.3.9 Point Dipole-Dipole Interaction.- 8.4 Deep Point Defects in Semiconductors and Insulators.- 8.4.1 Substitutional Donors with ?z = 1.- 8.4.2 Substitutional Donors with ?z = 2.- 8.4.3 Interstitial Deep Donors.- 8.4.4 Shallow Acceptors with ?z = -1.- 8.4.5 Deep Acceptors with ?z = -2.- 8.4.6 Vacancies.- 8.4.7 Point Defects in Ionic Solids.- 8.4.8 3d Transition Metal Defects.- 8.4.9 Interstitial 3d TM Defects.- 8.5 Shallow Defects: The Effective Mass Approximation …