Festkörperprobleme 30: Plenary Lectures Of The Divisions Semiconductor Physics Thin Films Dynamics And Statistical Physics Magnetism Metal Physics Surface Physics Low Temperature Physics Molecular Physics Of The German Physical Society (dpg), Regensburg, March 26 To 30, 1990

FESTKORPERPROB LEME ADVANCES IN SOLID STATE PHYSICS 30 FESTK(JRPER PROBLEME ADVANCES IN SOLID STATE PHYSICS 30 Plenary Lectures of the Divisions Semiconductor Physics Thin Films Dynamics and Statistical Physics Magnetism Metal Physics Surface Physics Low Temperature Physics Molecular Physics of the German Physical Society (DPG), Regensburg, March 26 to 30, 1990 Edited by Ulrich RSssler [v-I Friedr.Vieweg & Sohn Braunschweig/Wiesbaden Editor: Prof. Dr. Ulrich ROssler Institut ftlr Theoretische Physik Uaiversit~tt Regeasburg P.O. Box 397 D-8400 Regensburg, F R G Vieweg is a subsidiary company of the Bertelsmann Publishing G r o u p International. All rights reserved © Friedr. Vieweg & Sohn Verlagsgesellschaft mbH, Braunschweig 1990 No part of this publication may be reproduced, stored in a retrieval system or transmitted, mechanical, by photocopying or otherwise, without prior permission of the copyright holder. Printed by Lengericher Handelsdruckerei, Lengerich Bound by Hunke + Schr6der, Iserlohn Cover design: Barbara Seebohm, Braunschweig Printed in the Federal Republic of Germany ISSN 0430-3393 ISBN 3-528-08038-8 Foreword In 1990 the historical city of Regensburg hosted for the first time the spring meeting of the Solid State Physics Division (Arbeitskreis Festk6rperphysik) o f the German Physical Society. With more than 3000 participants, among which about 200 physicists from German Democratic Republic attended for the first time, the meeting was the biggest in this conference series so far. It was the more important, that the plenary and invited lectures played their role as attractors and as first hand information on current topics provided by experts in the field. A selection of these lectures, which exhibit the wide spectrum of research activities and important recent achievements in Solid State Physics, is published in this volume. F o r their work on quantum dynamics of hydrogen in metals H. Grabert and H. Wipf received the Walter-Schottky prize 1990. On occasion of the tenth anniversary of the quantum Hall effect its metrological consequences, its present understanding and open questions are reviewed in three contributions. A series o f papers on nonlinear phenomena in the optical and transport properties of semiconductors were presented at a symposium during the conference. The continued interest in small semiconductor structures is reflected in articles on their preparation, characterization and new physical problems. Besides various aspects of bulk semiconductors: metalinsulator transition, spectroscopy with ultra-short laser pulses, the dynamical Stark-effect and solar cells, this volume extends also to photoconductive polymers, high-To superconductors, characterization of thin films and the diluted 3D-Ising model. These topics cover the whole spectrum from fundamental problems to applications, which is typical for solid state physics. As for the previous volume the authors have been asked to deliver their manuscripts in camera-ready form according to detailed TEX-instructions. Only the smaller part of the submitted papers met these requirements and minor corrections or even complete retyping was necessary. This has been accomplished with great care by Angela Reisser who thus earns the merit of the homogeneous appearance o f the volume. The cooperation with Bj6rn Gondesen from the Vieweg publishing house is thankfully acknowledged. Regensburg, May 1990 Ulrich R6ssler V Contents Herrnann Grabert and Helmut W i p f Tunneling of Hydrogen in Metals ................................................... Klaus yon Klitzing Ten Years Quantum Hall Effect .................................................... 25 Markus Biittiker Edges, Contacts and the