Low-dimensional materials are of fundamental interest in physics and chemistry and have also found a wide variety of technological applica tions in fields ranging from microelectronics to optics. Since 1986, several seminars and summer schools devoted to low-dimensional systems have been supported by NATO. The present one, Physics, Fabrication and Applications of Multilayered structures, brought together specialists from different fields in order to review fabrication techniques, charac terization methods, physics and applications. Artificially layered materials are attractive because alternately layering two (or more) elements, by evaporation or sputtering, is a way to obtain new materials with (hopefully) new physical properties that pure materials or alloys do not allow. These new possibilities can be ob tained in electronic transport, optics, magnetism or the reflectivity of x-rays and slow neutrons. By changing the components and the thickness of the layers one can track continuously how the new properties appear and follow the importance of the multilayer structure of the materials. In addition, with their large number of interfaces the study of inter face properties becomes easier in multilayered structures than in mono layers or bilayers. As a rule, the role of the interface quality, and also the coupling between layers, increases as the thickness of the layer decreases. Several applications at the development stage require layer thicknesses of just a few atomic layers.

The fields of X-Ray Spectroscopy in Atomic and Solid State Physics have undergone spectacular growth, sometimes rather anarchic, during the past decade. The old mold of X-ray spectroscopy has been burst, and this ASI provided an in-depth exploration of theory and recently developed techniques; however, some work still needs to be done to create a new frame and reduce anarchy in the field. The purpose of this Institute was to gather atomic and solid state physicists working in theoretical and new experimental techniques recently developed. The lectures were concerned with, among others, the following fields: theory of X-ray near-edge structure, XPS and AES with conventional and synchrotron radiation sources, PIXE, EXAFS, SEXAFS, XRF, SXS, and molecular spectroscopy. The Institute considered in detail some of these experimental tech niques and the pertinent theoretical interpretations by selecting an important list of lectures which summarize the scientific contents of the ASI. The truly international character of this NATO ASI, its size, and the high quality of the lecturers contributed to make this school a very fruitful scientific meeting. Two to four general lectures were given each working day and three afternoons were reserved for presentation of current work in the form of posters. We think that these poster presentations reflect the current research work of the participants.

The papers contained in the volume represent lectures delivered as a 1983 NATO ASI, held at Urbino, Italy. The lecture series was designed to identify the key submicron and ultrasubmicron device physics, transport, materials and contact issues. Nonequilibrium transport, quantum transport, interfacial and size constraints issues were also highlighted. The ASI was supported by NATO and the European Research Office. H. L. Grubin D. K. Ferry C. Jacoboni v CONTENTS MODELLING OF SUB-MICRON DEVICES.................. .......... 1 E. Constant BOLTZMANN TRANSPORT EQUATION... ... ...... .................... 33 K. Hess TRANSPORT AND MATERIAL CONSIDERATIONS FOR SUBMICRON DEVICES. . .. . . . . .. . . . .. . .. . .... ... .. . . . .. . . . .. . . . . . . . . . . 45 H. L. Grubin EPITAXIAL GROWTH FOR SUB MICRON STRUCTURES.................. 179 C. E. C. Wood INSULATOR/SEMICONDUCTOR INTERFACES.......................... 195 C. W. Wilms en THEORY OF THE ELECTRONIC STRUCTURE OF SEMICONDUCTOR SURFACES AND INTERFACES......................................... 223 C. Calandra DEEP LEVELS AT COMPOUND-SEMICONDUCTOR INTERFACES........... 253 W. Monch ENSEMBLE MONTE CARLO TECHNIqUES............................. 289 C. Jacoboni NOISE AND DIFFUSION IN SUBMICRON STRUCTURES................. 323 L. Reggiani SUPERLATTICES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361 . . . . . . . . . . . . K. Hess SUBMICRON LITHOGRAPHY 373 C. D. W. Wilkinson and S. P. Beaumont QUANTUM EFFECTS IN DEVICE STRUCTURES DUE TO SUBMICRON CONFINEMENT IN ONE DIMENSION.... ....................... 401 B. D. McCombe vii viii CONTENTS PHYSICS OF HETEROSTRUCTURES AND HETEROSTRUCTURE DEVICES..... 445 P. J. Price CORRELATION EFFECTS IN SHORT TIME, NONS TAT I ONARY TRANSPORT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 477 . . . . . . . . . . . . J. J. Niez DEVICE-DEVICE INTERACTIONS............ ...................... 503 D. K. Ferry QUANTUM TRANSPORT AND THE WIGNER FUNCTION................... 521 G. J. Iafrate FAR INFRARED MEASUREMENTS OF VELOCITY OVERSHOOT AND HOT ELECTRON DYNAMICS IN SEMICONDUCTOR DEVICES............. 577 S. J. Allen, Jr.

The ability to understand and control the unique properties of interfaces has created an entirely new field of magnetism, with profound impact in technology and serving as the basis for a revolution in electronics. Our understanding of the physics of magnetic nanostructures has also advanced significantly. This rapid development has generated a need for a comprehensive treatment that can serve as an introduction to the field for those entering it from diverse fields, but which will also serve as a timely overview for those already working in this area. The four-volume work Ultra-Thin Magnetic Structures aims to fulfill this dual need. The original two volumes – now available once more – are "An Introduction to the Electronic, Magnetic and Structural Properties" (Vol. I) and Measurement Techniques and Novel Magnetic Properties (this volume). Two new volumes, "Fundamentals of Nanomagnetism" and "Applications of Nanomagnetism," extend and complete this comprehensive work by presenting the foundations of spintronics.

This volume comprises the proceedings of the NATO Advanced Research Workshop on the Science and Engineering of 1- and O-dimensional semiconductors held at the University of Cadiz from 29th March to 1st April 1989, under the auspices of the NATO International Scientific Exchange Program. There is a wealth of scientific activity on the properties of two-dimensional semiconductors arising largely from the ease with which such structures can now be grown by precision epitaxy techniques or created by inversion at the silicon-silicon dioxide interface. Only recently, however, has there burgeoned an interest in the properties of structures in which carriers are further confined with only one or, in the extreme, zero degrees of freedom. This workshop was one of the first meetings to concentrate almost exclusively on this subject: that the attendance of some forty researchers only represented the community of researchers in the field testifies to its rapid expansion, which has arisen from the increasing availability of technologies for fabricating structures with small enough (sub - O. I/tm) dimensions. Part I of this volume is a short section on important topics in nanofabrication. It should not be assumed from the brevity of this section that there is little new to be said on this issue: rather that to have done justice to it would have diverted attention from the main purpose of the meeting which was to highlight experimental and theoretical research on the structures themselves.