Semiconductor Interfaces

Semiconductor Surfaces and Interfaces deals with structural and electronic properties of semiconductor surfaces and interfaces. The first part introduces the general aspects of space-charge layers, of clean-surface and adatom-included surfaces states, and of interface states. It is followed by a presentation of experimental results on clean and adatom-covered surfaces which are explained in terms of simple physical and chemical concepts and models. Where available, results of more refined calculations are considered. A final chapter is devoted to the band lineup at semiconductor interfaces.

This third edition has been thoroughly revised and updated. In particular it now includes an extensive discussion of the band lineup at semiconductor interfaces. The unifying concept is the continuum of interface-induced gap states.

Using the continuum of interface-induced gap states (IFIGS) as a unifying theme, Mönch explains the band-structure lineup at all types of semiconductor interfaces. These intrinsic IFIGS are the wave-function tails of electron states, which overlap a semiconductor band-gap exactly at the interface, so they originate from the quantum-mechanical tunnel effect. He shows that a more chemical view relates the IFIGS to the partial ionic character of the covalent interface-bonds and that the charge transfer across the interface may be modeled by generalizing Pauling?s electronegativity concept. The IFIGS-and-electronegativity theory is used to quantitatively explain the barrier heights and band offsets of well-characterized Schottky contacts and semiconductor heterostructures, respectively.

The trend towards miniaturisation of microelectronic devices and the search for exotic new optoelectronic devices based on multilayers confer a crucial role on semiconductor interfaces. Great advances have recently been achieved in the elaboration of new thin film materials and in the characterization of their interfacial properties, down to the atomic scale, thanks to the development of sophisticated new techniques. This book is a collection of lectures that were given at the International Winter School on Semiconductor Interfaces: Formation and Properties held at the Centre de Physique des Rouches from 24 February to 6 March, 1987. The aim of this Winter School was to present a comprehensive review of this field, in particular of the materials and methods, and to formulate recom mendations for future research. The following topics are treated: (i) Interface formation. The key aspects of molecular beam epitaxy are emphasized, as well as the fabrication of artificially layered structures, strained layer superlattices and the tailoring of abrupt doping profiles. (ii) Fine characterization down to the atomic scale using recently devel oped, powerful techniques such as scanning tunneling microscopy, high reso lution transmission electron microscopy, glancing incidence x-ray diffraction, x-ray standing waves, surface extended x-ray absorption fine structure and surface extended energy-loss fine structure. (iii) Specific physical properties of the interfaces and their prospective applications in devices. We wish to thank warmly all the lecturers and participants, as well as the organizing committee, who made this Winter School a success.

This book focuses exclusively on control of interfacial properties and structures for semiconductor device applications from the point of view of improving and developing novel electrical properties. The following topics are covered: metal-semiconductors, semiconductor hetero-interfaces, characterization, semiconducting new materials, insulator-semiconductor, interfaces in device, control of interface formation, control of interface properties, contact metallization. A variety of up-to-date research topics such as atomic layer epitaxy, atomic layer passivation, atomic scale characterization including STM and SR techniques, single ion implementation, self-organization crystal growth, in situ measurements for process control and extremely high-spatial resolution analysis techniques, are also included. Furthermore it bridges the macroscopic, mesoscopic, and atomic-scale regimes of semicondutor interfaces, describing the state of the art in forming, controlling and characterizating unique semiconductor interfaces, which will be of practical importance in advanced devices. Intended for both technologists who require an up-to-date assessment of methods for interface formation, processing and characterization, and solid state researchers who desire the latest developments in understanding the basic mechanisms of interface physics, chemistry and electronics, this book will be a welcome addition to the existing literature.

This book represents the work presented at a NATO Advanced Research Workshop on "Metallization and Metal-Semiconductor Interfaces", held at the Technical University of Munich, Garching, W. Germany from 22-26 August 1988. The major focus of the workshop was to evaluate critically the progress made in the area of metal-semiconductor interfaces. The underlying theme was the mechanism of Schottky barrier formation and a serious as sessment of the various models. A significant fraction of the workshop time was also spent in discussing the interaction of alkali metals with semiconductors. Alkali metals on semi conductors form ordered overlayers and the resulting system often exhibits one-dimensional metallic properties. The nature of their interaction has introduced new and exciting com plexities and this was pursued at length during the lively discussions at the workshop. A half a day was devoted to Scanning Tunneling Microscopy, the emphasis being on its utility in providing structural and electronic character of low-coverage regime. The book should pro vide readers with the most current status of the research activity in the general area of metal-semiconductor interfaces at an international level. It should also serve as an excellent introduction to the field, since sufficient review type of material has also been included The workshop organizers, Dr. I. P. Batra (Director), mM Almaden Research Center, San Jose, Prof. S. Ciraci, Bilkent University, Ankara, Prof. C. Y. Pong, University of California, Davis, Prof. Dr. F. Koch (Local Chairman), Technical University Munich, Garching, Dr. H.