Nonequilibrium Phonons In Nonmetallic Crystals

The physics of nonequilibrium electrons and phonons in semiconductors is an important branch of fundamental physics that has many practical applications, especially in the development of ultrafast and ultrasmall semiconductor devices. This volume is devoted to different trends in the field which are presently at the forefront of research. Special attention is paid to the ultrafast relaxation processes in bulk semiconductors and two-dimensional semiconductor structures, and to their study by different spectroscopic methods, both pulsed and steady-state. The evolution of energy and space distribution of nonequilibrium electrons and the relaxation kinetics of hot carriers and phonons are considered under various conditions such as temperature, doping and pumping intensity by leading experts in the field.

Phonons are always present in the solid state even at an absolute temperature of 0 K where zero point vibrations still abound. Moreover, phonons interact with all other excitations of the solid state and, thereby, influence most of its properties. Historically experimental information on phonon transport came from measurements of thermal conductivity. Over the past two decades much more, and much more detailed, information on phonon transport and on many of the inherent phonon interaction processes have come to light from experiments which use nonequilibrium phonons to study their dynamics. The resultant research field has most recently blossomed with the development of ever more sophisticated experimental and theoretical methods which can be applied to it. In fact, the field is moving so rapidly that new members of the research community have difficulties in keeping up to date. This NATO Advanced Study Institute (ASI) was organized with the objective of overcoming the information barrier between those expert in the field and those who are new to it. Thus it was decided to (i) organize a set of tutorially based lectures covering most of the important facets in the field, and (ii) to produce an Institute proceedings which would serve both as the first general textbook, as well as a valuable reference book, for this field of knowledge.

Laser-based optical spectroscopies are powerful and versatile techniques that are continuing to evolve and find new applications. This book presents reviews of recent progress in our understanding of the spectra and dynamical processes of optically excited states of condensed matter, focusing on the advances made possible by the application of laser-based optical spectroscopies. Reviews are given of the optical properties of crystalline and amorphous semiconducting materials and structures, the properties of defect centers in insulators, two-photon nonlinear processes in insulators, optical energy diffusion in inorganic materials, and relaxation in organic materials. The individual chapters emphasize the methodology common to the various investigations. The volume is designed to be suitable as an introduction to applied laser spectroscopy of solids, as well as providing an update on the status of the field.

This book is dedicated to Professor Leonid V Keldysh. His brilliant contributions to condensed matter physics include the Franz-Keldysh effect, an electron-hole liquid, the nonequilibrium (Keldysh) diagram technique, Bose-Einstein condensation (of excitons) and a ``metal-dielectric'' transition, acoustically-induced superlattices, multi-photon transitions and impact ionization in solids. In many respects, his work influenced and formed the paradigm of modern condensed matter physics. As a result, many famous researchers in the field have enthusiastically provided unique contributions to the book.

There have been few books devoted to the study of phonons, a major area of condensed matter physics. The Physics of Phonons is a comprehensive theoretical discussion of the most important topics, including some topics not previously presented in book form. Although primarily theoretical in approach, the author refers to experimental results wherever possible, ensuring an ideal book for both experimental and theoretical researchers. The author begins with an introduction to crystal symmetry and continues with a discussion of lattice dynamics in the harmonic approximation, including the traditional phenomenological approach and the more recent ab initio approach, detailed for the first time in this book. A discussion of anharmonicity is followed by the theory of lattice thermal conductivity, presented at a level far beyond that available in any other book. The chapter on phonon interactions is likewise more comprehensive than any similar discussion elsewhere. The sections on phonons in superlattices, impure and mixed crystals, quasicrystals, phonon spectroscopy, Kapitza resistance, and quantum evaporation also contain material appearing in book form for the first time. The book is complemented by numerous diagrams that aid understanding and is comprehensively referenced for further study. With its unprecedented wide coverage of the field, The Physics of Phonons will be indispensable to all postgraduates, advanced undergraduates, and researchers working on condensed matter physics.

This book presents the recent advances in spectroscopy and theoretical modeling relevant to the interpretation of luminescence and laser phenomena in solid state materials. The available solid state matrices in crystalline and glassy states and the full range of activaters-transition metal ions, rare earth ions and actinides are considered here. Processes of activator excitation, energy transfer between activators and relaxation of excited states are particularly stressed.

The proceedings reflect the Twelfth International Conference on Defects in Insulating Materials, covering topics on point defects and extended defects including theory and computer simulation in various insulating materials, as well as applications in laser physics, imaging, data storage and radioactive waste disposal.