In the last ten years, the physics and technology of low dimensional structures has experienced a tremendous development. Quantum structures with vertical and lateral confinements are now routinely fabricated with feature sizes below 100 run. While quantization of the electron states in mesoscopic systems has been the subject of intense investigation, the effect of confinement on lattice vibrations and its influence on the electron-phonon interaction and energy dissipation in nanostructures received atten tion only recently. This NATO Advanced Research Workshop on Phonons in Sem iconductor Nanostructures was a forum for discussion on the latest developments in the physics of phonons and their impact on the electronic properties of low-dimensional structures. Our goal was to bring together specialists in lattice dynamics and nanos tructure physics to assess the increasing importance of phonon effects on the physical properties of one-(lD) and zero-dimensional (OD) structures. The Workshop addressed various issues related to phonon physics in III-V, II-VI and IV semiconductor nanostructures. The following topics were successively covered: Models for confined phonons in semiconductor nanostructures, latest experimental observations of confined phonons and electron-phonon interaction in two-dimensional systems, elementary excitations in nanostructures, phonons and optical processes in reduced dimensionality systems, phonon limited transport phenomena, hot electron effects in quasi - ID structures, carrier relaxation and phonon bottleneck in quantum dots."

Technological advances in semiconductor growth has opened a broad horizon for semiconductor physics and applications during the past 20 years. High quality two-. dimensional systems are achieved with nearly atomic precision by direct epitaxial growth. Such structures led to novel applications like low noise high frequency modulation doped field effect transistors and quantum well lasers. Semiconductor heterostructures of lower dimensionality like quantum wires and quantum dots are not yet as mature, partly due to the lack in precision oflateral structuring technology. In recent years, however, there was an enormous progress in novel epitaxial growth methods. This opens a wide new area of basic and applied semiconductor physics with the hope of novel applications in near future making use of the advantageous properties of one- and zero-dimensional systems. Ideas for future device applications mainly stem from the altered density of states being discrete or atomic-like for quantum dots. Optical spectroscopy has played and is playing a crucial role in the advancement of this fascinating field of semiconductor physics. The NATO school organized at Bilkent University in Ankara and in Antalya brought together experts in this field and newcomers, especially young Ph. D. students and postdocs, to learn about recent developments and to discuss open questions in the area of optical spectroscopy of low dimensional semiconductors. The school turned out to be extremely fruitful and there was a great enthusiasm among the lecturers and students during the whole two weeks.

This volume contains invited and contributed papers of the Ninth International Conference on Hot Carriers in Semiconductors (HCIS-9), held July 3 I-August 4, 1995 in Chicago, Illinois. In all, the conference featured 15 invited oral presentations, 60 contributed oral presentations, and 105 poster presentations, and an international contingent of 170 scientists. As in recent conferences, the main themes of the conference were related to nonlinear transport in semiconductor heterojunctions and included Bloch oscillations, laser diode structures, and femtosecond spectroscopy. Interesting questions related to nonlinear transport, size quantization, and intersubband scattering were addressed that are relevant to the new quantum cascade laser. Many lectures were geared toward quantum wires and dots and toward nanostructures and mesoscopic systems in general. It is expected that such research will open new horizons to nonlinear transport studies. An attempt was made by the program committee to increase the number of presen tations related directly to devices. The richness of nonlocal hot electron effects that were discussed as a result, in our opinion, suggests that future conferences should further encourage reports on such device research. On behalf of the Program and International Advisory Committees, we thank the participants, who made the conference a successful and pleasant experience, and the support of the Army Research Office, the Office of Naval Research, and the Beckman Institute of the University of Illinois at Urbana-Champaign. We are also indebted to Mrs. Sara Starkey and Mrs."

Large computational resources are of ever increasing importance for the simulation of semiconductor processes, devices and integrated circuits. The Workshop on Computational Electronics was intended to be a forum for the dis cussion of the state-of-the-art of device simulation. Three major research areas were covered: conventional simulations, based on the drift-diffusion and the hydrodynamic models; Monte Carlo methods and other techniques for the solution of the Boltzmann transport equation; and computational approaches to quantum transport which are relevant to novel devices based on quantum interference and resonant tunneling phenomena. Our goal was to bring together researchers from various disciplines that contribute to the advancement of device simulation. These include Computer Sci ence, Electrical Engineering, Applied Physics and Applied Mathematics. The suc cess of this multidisciplinary formula was proven by numerous interactions which took place at the Workshop and during the following three-day Short Course on Computational Electronics. The format of the course, including a number of tutorial lectures, and the large attendance of graduate students, stimulated many discussions and has proven to us once more the importance of cross-fertilization between the different disciplines."

Technological advances in semiconductor growth has opened a broad horizon for semiconductor physics and applications during the past 20 years. High quality two-. dimensional systems are achieved with nearly atomic precision by direct epitaxial growth. Such structures led to novel applications like low noise high frequency modulation doped field effect transistors and quantum well lasers. Semiconductor heterostructures of lower dimensionality like quantum wires and quantum dots are not yet as mature, partly due to the lack in precision oflateral structuring technology. In recent years, however, there was an enormous progress in novel epitaxial growth methods. This opens a wide new area of basic and applied semiconductor physics with the hope of novel applications in near future making use of the advantageous properties of one- and zero-dimensional systems. Ideas for future device applications mainly stem from the altered density of states being discrete or atomic-like for quantum dots. Optical spectroscopy has played and is playing a crucial role in the advancement of this fascinating field of semiconductor physics. The NATO school organized at Bilkent University in Ankara and in Antalya brought together experts in this field and newcomers, especially young Ph. D. students and postdocs, to learn about recent developments and to discuss open questions in the area of optical spectroscopy of low dimensional semiconductors. The school turned out to be extremely fruitful and there was a great enthusiasm among the lecturers and students during the whole two weeks.

In the last ten years, the physics and technology of low dimensional structures has experienced a tremendous development. Quantum structures with vertical and lateral confinements are now routinely fabricated with feature sizes below 100 run. While quantization of the electron states in mesoscopic systems has been the subject of intense investigation, the effect of confinement on lattice vibrations and its influence on the electron-phonon interaction and energy dissipation in nanostructures received atten tion only recently. This NATO Advanced Research Workshop on Phonons in Sem iconductor Nanostructures was a forum for discussion on the latest developments in the physics of phonons and their impact on the electronic properties of low-dimensional structures. Our goal was to bring together specialists in lattice dynamics and nanos tructure physics to assess the increasing importance of phonon effects on the physical properties of one-(lD) and zero-dimensional (OD) structures. The Workshop addressed various issues related to phonon physics in III-V, II-VI and IV semiconductor nanostructures. The following topics were successively covered: Models for confined phonons in semiconductor nanostructures, latest experimental observations of confined phonons and electron-phonon interaction in two-dimensional systems, elementary excitations in nanostructures, phonons and optical processes in reduced dimensionality systems, phonon limited transport phenomena, hot electron effects in quasi - ID structures, carrier relaxation and phonon bottleneck in quantum dots."

Large computational resources are of ever increasing importance for the simulation of semiconductor processes, devices and integrated circuits. The Workshop on Computational Electronics was intended to be a forum for the dis cussion of the state-of-the-art of device simulation. Three major research areas were covered: conventional simulations, based on the drift-diffusion and the hydrodynamic models; Monte Carlo methods and other techniques for the solution of the Boltzmann transport equation; and computational approaches to quantum transport which are relevant to novel devices based on quantum interference and resonant tunneling phenomena. Our goal was to bring together researchers from various disciplines that contribute to the advancement of device simulation. These include Computer Sci ence, Electrical Engineering, Applied Physics and Applied Mathematics. The suc cess of this multidisciplinary formula was proven by numerous interactions which took place at the Workshop and during the following three-day Short Course on Computational Electronics. The format of the course, including a number of tutorial lectures, and the large attendance of graduate students, stimulated many discussions and has proven to us once more the importance of cross-fertilization between the different disciplines."