Doping in III-V Semiconductors


Book Description

This is the first book to describe thoroughly the many facets of doping in compound semiconductors. Equal emphasis is given to the fundamental materials physics and to the technological aspects of doping. The author describes various doping techniques, including doping during epitaxial growth, doping by implantation, and doping by diffusion. The key characteristics of all dopants that have been employed in III-V semiconductors are discussed. In addition, general characteristics of dopants are analyzed, including the electrical activity, saturation, amphotericity, autocompensation, and maximum attainable dopant concentration. Redistribution effects are important in semiconductor microstructures. Linear and non-linear diffusion, different microscopic diffusion mechanisms, surface segregation, surface drift, surface migration, impurity-induced disordering, and the respective physical driving mechanisms are illustrated. Topics related to basic impurity theory include the hydrogenic model for shallow impurities, linear screening, density of states, classical and quantum statistics, the law of mass action, as well as many analytic approximations for the Fermi-Dirac integral for three-, two- and one dimensional systems. The timely topic of highly doped semiconductors, including band tails, impurity bands, bandgap renormalization, the Mott transition, and the Burstein-Moss shift, is discussed as well. Doping is essential in many semiconductor heterostructures including high-mobility selectively doped heterostructures, quantum well and quantum barrier structures, doping superlattice structures and d-doping structures. Technologically important deep levels are summarized, including Fe, Cr, and the DX-center, the EL2 defect, and rare-earth impurities. The properties of deep levels are presented phenomenologically, including emission, capture, Shockley-Read recombination, the Poole-Frenkel effect, lattice relaxation, and other effects. The final chapter is dedicated to the experimental characterization of impurities. This book will be of interest to graduate students, researchers and development engineers in the fields of electrical engineering, materials science, physics, and chemistry working on semiconductors. The book may also be used as a text for graduate courses in electrical engineering and materials science.




Defects in Semiconductors


Book Description

This volume, number 91 in the Semiconductor and Semimetals series, focuses on defects in semiconductors. Defects in semiconductors help to explain several phenomena, from diffusion to getter, and to draw theories on materials' behavior in response to electrical or mechanical fields. The volume includes chapters focusing specifically on electron and proton irradiation of silicon, point defects in zinc oxide and gallium nitride, ion implantation defects and shallow junctions in silicon and germanium, and much more. It will help support students and scientists in their experimental and theoretical paths. - Expert contributors - Reviews of the most important recent literature - Clear illustrations - A broad view, including examination of defects in different semiconductors







DX Centers


Book Description

Donors in AlGaAs and Related Compounds




Trap Level Spectroscopy in Amorphous Semiconductors


Book Description

Although amorphous semiconductors have been studied for over four decades, many of their properties are not fully understood. This book discusses not only the most common spectroscopic techniques but also describes their advantages and disadvantages. - Provides information on the most used spectroscopic techniques - Discusses the advantages and disadvantages of each technique




Properties of Impurity States in Superlattice Semiconductors


Book Description

A NATO workshop on "The Properties of Impurity States in Semiconductor Superlattices" was held at the University of Essex, Colchester, United Kingdom, from September 7 to 11, 1987. Doped semiconductor superlattices not only provide a unique opportunity for studying low dimensional electronic behavior, they can also be custom-designed to exhibit many other fascinating el~ctronic properties. The possibility of using these materials for new and novel devices has further induced many astonishing advances, especially in recent years. The purpose of this workshop was to review both advances in the state of the art and recent results in various areas of semiconductor superlattice research, including: (i) growth and characterization techniques, (ii) deep and shallow im purity states, (iii) quantum well states, and (iv) two-dimensional conduction and other novel electronic properties. This volume consists of all the papers presented at the workshop. Chapters 1-6 are concerned with growth and characterization techniques for superlattice semiconductors. The question of a-layer is also discussed in this section. Chapters 7-15 contain a discussion of various aspects of the impurity states. Chapters 16- 22 are devoted to quantum well states. Finally, two-dimensional conduction and other electronic properties are described in chapters 23-26.




Point Defects in Semiconductors II


Book Description

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.




Point Defects in Semiconductors I


Book Description

From its early beginning before the war, the field of semiconductors has developped as a classical example where the standard approximations of 'band theory' can be safely used to study its interesting electronic properties. Thus in these covalent crystals, the electronic structure is only weakly coupled with the atomic vibrations; one-electron Bloch functions can be used and their energy bands can be accurately computed in the neighborhood of the energy gap between the valence and conduction bands; nand p doping can be obtained by introducing substitutional impurities which only introduce shallow donors and acceptors and can be studied by an effective-mass weak-scattering description. Yet, even at the beginning, it was known from luminescence studies that these simple concepts failed to describe the various 'deep levels' introduced near the middle of the energy gap by strong localized imperfections. These imperfections not only include some interstitial and many substitutional atoms, but also 'broken bonds' associated with surfaces and interfaces, dis location cores and 'vacancies', i.e., vacant iattice sites in the crystal. In all these cases, the electronic structure can be strongly correlated with the details of the atomic structure and the atomic motion. Because these 'deep levels' are strongly localised, electron-electron correlations can also playa significant role, and any weak perturbation treatment from the perfect crystal structure obviously fails. Thus, approximate 'strong coupling' techniques must often be used, in line' with a more chemical de scription of bonding.




Transition Metal Impurities in Semiconductors


Book Description

This book discusses the theory of the electron states of transition metal impurities in semiconductors in connection with the general theory of isoelectronic impurities. It contains brief descriptions of the experimental data available for transition metal impurities belonging to iron, palladium and platinum groups and for rare-earth impurities in elemental semiconductors (III-IV, II-VI and IV-VI compounds) and in several oxide compounds (Ti2, BaTiO3, SrTiO3). Also included are applications of the theory to the optical, electrical and resonance properties of semiconductors doped by the transition metal impurities.The book presents a theory unifying previously proposed ligand-field and band descriptions of transition metal impurities. It describes the theory in the context of the general theory of neutral impurities in semiconductors and demonstrates the capabilities of this description to explain the basic experimental properties of semiconductors doped by transition metal impurities. A detailed discussion of various experimental results and their theoretical interpretation is carried out.This book comprises three parts. The first two parts consider several exactly solvable models and describe numerical techniques. All the models and simulations constitute a general pattern describing transition metal and rare-earth impurities in semiconductors. The final part uses this theory in order to address various experimentally observed properties of these systems.




Color Centers in Semiconductors for Quantum Applications


Book Description

Point defects in semiconductors have been and will continue to be relevant for applications. Shallow defects realize transistors, which power the modern age of information, and in the not-too-distant future, deep-level defects could provide the foundation for a revolution in quantum information processing. Deep-level defects (in particular color centers) are also of interest for other applications such as a single photon emitter, especially one that emits at 1550 nm, which is the optimal frequency for long-range communication via fiber optics. First-principle calculations can predict the energies and optical properties of point defects. I performed extensive convergence tests for magneto-optical properties, such as zero phonon lines, hyperfine coupling parameters, and zero-field splitting for the four different configurations of the divacancy in 4H-SiC. Comparing the converged results with experimental measurements, a clear identification of the different configurations was made. With this approach, I also identified all configurations for the silicon vacancy in 4H-SiC as well as the divacancy and silicon vacancy in 6H-SiC. The same method was further used to identify two additional configurations belonging to the divacancy present in a 3C stacking fault inclusion in 4H-SiC. I extended the calculated properties to include the transition dipole moment which provides the polarization, intensity, and lifetime of the zero phonon lines. When calculating the transition dipole moment, I show that it is crucial to include the self-consistent change of the electronic orbitals in the excited state due to the geometry relaxation. I tested the method on the divacancy in 4H-SiC, further strengthening the previous identification and providing accurate photoluminescence intensities and lifetimes. Finding stable point defects with the right properties for a given application is a challenging task. Due to the vast number of possible point defects present in bulk semiconductor materials, I designed and implemented a collection of automatic workflows to systematically investigate any point defects. This collection is called ADAQ (Automatic Defect Analysis and Qualification) and automates every step of the theoretical process, from creating defects to predicting their properties. Using ADAQ, I screened about 8000 intrinsic point defect clusters in 4H-SiC. This thesis presents an overview of the formation energy and the most relevant optical properties for these single and double point defects. These results show great promise for finding new color centers suitable for various quantum applications.