Springer Proceedings in Physics 79 Springer Proceedings in Physics Managing Editor: H. K. V. Lotsch 46 Cellular Automata and Modeling 64 Superconducting Devices and Their Applications of Complex Physical Systems Editors: H. Koch and H. Liibbig Editors: P. Manneville, N. Boccara, 65 Presellt alld Future of High-Energy Physics G. Y. Vichniac, and R. Bidaux Editors. K.-l. Aoki and M. Kobayashi 47 Number Theory and Physics 66 The Structure and Conformation Editors: l.-M. Luck, P. Moussa, of Amphiphilic Membranes and M. Waldschmidt Editors: R. Lipowsky, D. Richter, and K. Kremer 48 Mally-Atom Interactiolls in Solids 67 Nonlinearity with Disorder Editors: R. M. Nieminen, M. 1. Puska, Editors: F. Abdullaev, A. R_ Bishop, and M. 1. Manninen and S. Pnevmatikos 49 Ultrafast Phenomena in Spectroscopy 68 Time-Resolved Vibrational Spectroscopy V Editors: E. Klose and B. Wilhelmi Editor: H. Takahashi 50 Magnetic Properties of Low-Dimensional 69 Evolution of Dynamical Structures Systems II: New Developmellls in Complex Systems Editors: L. M. Falicov, F. Mejfa-Lira, Editors: R. Friedrich and A. Wunderlin and J. L. Moran-L6pez 70 Computational Approaches 51 The Physics and Chemistry in COlldensed-Matter Physics of Organic Superconductors Editors: S. Miyashita, M. Imada, Editors: G. Saito and S. Kagoshima and H. Takayama 52 Dynamics and Patterns in Complex Fluids: 71 Amorphous and Crystalline Silicon Carbide IV New Aspects of the Physics-Chemistry Editors: C. Y. Yang, M. M. Rahman, Intetface and G. L. Harris Editors: A. Onuki and K. Kawasaki 72 Computer Simulatioll Studies 53 Computer Simulatioll Studies ill Condensed-Matter Physics IV ill Condellsed-Matter Physics III Editors: D. P. Landau, K. K. Mon, Editors: D. P. Landau, K. K. Mon, and H.-B. Schiittler and H.-B. Schiittler 73 Sutface Scietlce: Principles and Applications 54 Polycrystalline Semiconductors II Editors: R. F. Howe, R. N. Lamb, Editors: J. H. Werner and H. P. Strunk and K. Wandelt 55 Nonlinear Dynamics and Qualllum Phenomena 74 Time-Resolved ill Optical Systems Vibrational Spectroscopy VI Editors: R. Vilaseca and R. Corbalan Editors: A. Lau, F. Siebert, 56 Amorphous and Crystalline Silicoll Carbide III, and W. Werncke and Other Group IV-IV Materials 75 Computer Simulation Studies ill Condensed-Matter Physics V Editors: G. L. Harris, M. G. Spencer, Editors: D. P. Landau, K. K. Mon, and C. Y. Yang and H.-B. Schiittler 57 Evolutionary Trends in the Physical Sciences 76 Computer SimulatiOlI Studies Editors: M. Suzuki and R. Kubo in Condensed-Matter Physics VI 58 New Trends in Nuclear Collective Dynamics Editors: D. P. Landau, K. K. Mon, Editors: Y. Abe, H. Horiuchi, and H.-B. Schiittler and K. Matsuyanagi 77 Quantum Optics VI 59 Exotic Atoms in Condensed Matter Editors: D. F. Walls and J. D. Harvey Editors: G. Benedek and H. Schneuwly 78 Computer Simulation Studies 60 The Physics and Chemistry in Condensed-Matter Physics VII of Oxide Superconductors Editors: D. P. Landau, K. K. Mon, Editors: Y. lye and H. Yasuoka and H.-B. Schiittler 61 Sutface X·Ray and Neutron Scattering 79 Nonlinear Dynamics and Pattern Formation Editors: H. Zabel and I. K. Robinson in Semiconductors and Devices 62 Sutface Science: Lectures on Basic Concepts Editor: F.-I. Niedernostheide and Applications Editors: F. A. Ponce and M. Cardona 63 Coherelll Raman Spectroscopy: Recelll Advances Editors: G. Marowsky and V. V. Smirnov Volumes 1-45 are listed at the end of the book F.-J. Niedemostheide (Ed.) Nonlinear Dynamics and Pattern Formation in Semiconductors and Devices Proceedings of a Symposium Organized Along with the International Conference on Nonlinear Dynamics and Pattern Formation in the Natural Environment Noordwijkerhout, The Netherlands, July 4-7, 1994 With 168 Figures Springer Dr. Franz-Josef Niedemostheide Institut fUr Angewandte Physik CorrensstraBe 2/4 0-48149 Miinster, Germany ISBN-13 :978-3-642-79508-4 e-ISBN-13:978-3-642-79506-0 DOl: 10.1007/978-3-642-79506-0 CIP data applied for This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcast ing, reproduction on microfilms or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable for prosecution under the German Copyright Law. © Springer-Verlag Berlin Heidelberg 1995 Softcover reprint of the hardcover I st edition 1995 The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Typesetting: Camera ready copy from the editor SPIN: 10479837 54/3144 -5432 I 0 -Printed on acid-free paper Preface This volume contains the contributions given at the symposium about Nonlinear Dynamics and Pattern Formation in Semiconductors and Devices in the frame of the International Conference on Nonlinear Dynamics and Pattern Formation in the Natural Environment (ICPF'94) held at Noordwijkerhout, the Netherlands July 4-7, 1994. As the conference aimed at the communication of new results and the exploration of new ideas concerning the theory of nonlinear dynamics and the study of pattern generating phenomena in diverse biological, chemical and physical systems, the central issues discussed during the semiconductor symposium involved fundamental self-organization processes and the physics of electrical instabilities in semiconductors and semiconductor devices. One of today's most challenging questions concerns the understanding of evolution of life. This in turn entails the question of how and on what condi tions patterns may arise from spatially uniform distributions and which minimal ingredients are necessary to achieve an aspired degree of complexity. In the last decades great progress in investigating this matter has been made in many fields of sciences, and fundamental concepts and basic mechanisms leading to the spontaneous appearance of spatial, temporal and spatia-temporal patterns have been developed. It turned out that many of the basic mechanisms appear in entirely different systems and, consequently, a concept worked out for the de scription of pattern formation in one system very often can be applied to a whole class of systems including systems of other fields. However, many questions are still unsolved and sometimes we are even far from a complete understanding of systems appearing very simple on a first view. In comparison with biological or chemical systems, physical systems have a great advantage concerning preparation, handling, and parameter controlling. Among the physical systems, semiconductors and semiconductor devices are most suitable for investigations concerning self-organization and pattern for mation because, on the one hand, a mature technology for their production is available and many theoretical works concerning the understanding of the micra scopic processes have been done. On the other hand, two basic presuppositions for the evolution of dissipative structures, the existence of nonlinearities and the possibility to force the system into a state far from equilibrium, can be achieved in semiconductors in manifold ways, leading to a huge variety of spatiotemporal patterns reaching from simple stationary kinks, solitary structures or periodic patterns over structures showing regular dynamic behaviour as the propaga tion of fronts, various oscillation modes of localized structures, target or spiral patterns to complex spatiotemporal patterns as chaotic oscillations of localized structures or irregular wavepatterns. The contributions included in this volume VI Preface take up many of these phenomena and discuss various mechanisms for pattern formation being of importance not only for semiconductors and devices. The articles are organized in the following way. In the first four chapters the main attention is focussed on the development of models describing pat tern formation in semiconductors and devices. Specific models concerning the dynamics of electric field domains in superlattices (Chapt. 1 and Chapt. 2), cur rent filaments in heterostructures (Chapt. 2) and nonlinear waves in extrinsic semiconductors (Chapt. 3) are presented and a survey of the properties of cur rent filaments and field domains is given (Chapt. 4). In the next five chapters, the emphasis is on experiments. The contributions deal with complex spatiotem poral luminescence patterns in a two-dimensional excitable medium consisting of a II-VI compound (Chapt. 5), nonlinear behaviour in organic and anor ganic crystals (Chapt. 6) and current filaments in gallium arsenide (Chapt. 7). Furthermore, stationary and dynamic patterns of current filaments and various bifurcation sequences in silicon ~n-~n (Chapt. 8) and ~i-n devices (Chapt. 9) are studied and corresponding models are developed. The last two chapters fo cus on possible applications of nonlinear phenomena. By means of low frequency oscillations appearing spontaneously, e. g., in II I-V compounds, deep levels in semiconductors are analyzed (Chapt. 10) and the application of maximum and minimum detectors based on the winner-takes-all mechanism is proposed for optical pattern recognition and optical fuzzy logic computing (Chapt. 11). I would like to thank the organizers of the ICPF'94, Prof. A. van Harten and Dr. A. Doelman, for their invitation to organize the semiconductor-symposium as part of the ICPF'94 and Dr. H. Lotsch from Springer-Verlag for his excellent cooperation. Munster, December 1994 F.-J. Niedernostheide Table of Contents 1 Dynamics of Electric Field Domains in Superlattices by L.L. Bonilla 1 1.1 Introduction.................... 1 1.2 Steady States . . . . . . . . . . . . . . . . . . . 5 1.2.1 Undoped Photoexcited SL, v = 0,1> 0 7 1.2.2 Doped SL, v > 0, 1 ~ 0 . . . . . . . . . 7 1.3 Phase Diagram and PC Time-Dependent Oscillations. 7 1.3.1 Undoped Photoexcited SL, v = 0,1> 0 7 1.3.2 Doped SL, v > 0, 1 ~ 0, 0 < c < 1 11 1.4 Asymptotics.. 13 1.5 Final Remarks ............... 18 2 Oscillatory Transport Instabilities and Complex Spatio-Temporal Dynamics in Semiconductors by E. Scholl, A. Wacker 21 2.1 Introduction........................... 21 2.2 Current Filaments in Crossed Electric and Magnetic Fields 23 2.3 Spiking in Layered Semiconductor Structures 30 2.3.1 Modelling the Dynamic Behaviour 31 2.3.2 Results ......... 33 2.4 Field Domains in Superlattices 36 2.4.1 The Model ....... 36 2.4.2 Static Characteristic . . 38 2.4.3 Spatia-Temporal Oscillations 40 2.5 Conclusions.............. 42 3 Space Charge Instabilities and Nonlinear Waves in Extrinsic Semiconductors by S. W. TeitstDorth, M.J. Bergmann, L.L. Bonilla 46 3.1 Introduction..................... 46 3.2 Full Rate Equation Model . . . . . . . . . . . . . 48 3.3 Non-Dimensionalization and the Reduced Model 51 VIII Table of Contents 3.4 The Case of Time-Independent (dc) Current Bias .. 54 3.4.1 Steady States and the J-E Curve ..... . 54 3.4.2 Periodic, Solitary and Monotone Wave Solutions 56 3.4.3 Dynamical Stability of Periodic, Solitary and Monotone Waves ............... . 58 3.5 The Case of dc Voltage Bias . . . . . . . . . 60 3.5.1 Position-Dependent Steady States . 60 3.5.2 Numerical Studies of Solitary Waves 62 3.5.3 Stability Analysis and Hopf Bifurcations from the Steady State ..... 66 3.6 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . 68 4 Autosolitons in Form of Current Fihunents and Electric Field Domains in Semiconductors and Devices by B.S. Kerner 70 4.1 Introduction.............................. 70 4.2 Formation of Current Filaments and Electric Field Domains in Semiconductors with Positive Differential Conductivity. 72 4.2.1 Current Filaments in Transistor Structures ... 72 4.2.2 Multi-Filament Current States in Reverse-Biased P-N Structures . . . . . . . . . . . . . . . . . . . 74 4.2.3 Current Filaments in Dense Electron Hole-Plasmas. 77 4.2.4 Electric Field Domains in Hot Electron Hole-Plasmas 80 4.3 Local Active and Damping Processes. Concept of "Activator" and "Inhibitor" . . . . . . . . . . . . . . . . . . . . . . . . . . .. 83 4.3.1 Possibility of the Appearance of Current Filaments or Elec- tric Field Domains and Form of the Current-Voltage Char- acteristic of Semiconductors . . 84 4.3.2 An Activator-Inhibitor Model. 86 4.4 Autosolitons in Semiconductors . . . 86 4.4.1 Form of Autosolitons . . . . . 86 4.4.2 Basic Types of Autosolitons . 89 4.5 Some Properties of Autosolitons .. 96 4.5.1 Main Types of Self-Organization Phenomena 96 4.5.2 "Nucleation Centre" for the Spontaneous Formation of Autosolitons in Semiconductors . . . . . . . . . . . . . .. 97 4.5.3 Effects Determining the Evolution of Autosolitons .... 99 4.5.4 Processes of Random Appearance and Disappearance of Autosolitons ......................... 103 4.5.5 Transitions Between Different Types of Autosolitons . . . 103 4.5.6 On Mechanisms of Spatiotemporal Chaos (Turbulence) in Semiconductors . 105 4.6 Conclusions.............................. 106 Table of Contents IX 5 Pattern Formation of the Electroluminescence in AC ZnS:Mn Devices by Ch. Goflen, F.-J. Niedernostheide, H.-G. Purwins 112 5.1 Introduction......... 112 5.2 Experimental Set-Up. . . . 113 5.3 Electroluminescence Basics 114 5.4 Experimental Results. . . . 116 5.4.1 Stationary Microfilaments and Hysteresis 116 5.4.2 Frontpropagation....... 117 5.4.3 Autowaves .............. 119 5.4.4 Mobile Filaments and Strings . . . . 120 5.4.5 Global Spatiotemporal Oscillations. 123 5.4.6 Summary of Experimental Results 126 5.5 Discussion................... 127 5.5.1 Formation of Microfilaments. . . . . 127 5.5.2 Comparison with Reaction-Diffusion Systems 128 5.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . 131 6 Structure Formation in Charge Density Wave Systems by M.J. Bunner, G. Heinz, A. Kittel, J. Parisi 133 6.1 The Peierls Transition . . . . . . . . . . . . 133 6.2 Materials .. . . . . . . . . . . . . . . . . . 134 6.3 The Electronic Transport in CDW Systems 135 6.4 Structure Formation of CDW Systems . . . 137 6.4.1 Metastability, Memory, and Hysteresis 137 6.4.2 Intermittent Oscillations and S-Shaped Negative Differen- tial Resistance ................ 139 6.4.3 Narrow-Band Noise and Broad-Band Noise 140 6.4.4 Mode-Locking.. 141 6.5 Conclusion and Outlook . . . . . . . . . . . . . . . 142 7 Current Filamentation in Dipolar Electric Fields by V. Novak, W. Pretti 144 7.1 Introduction...................... 144 7.2 Stationary Current Filaments in a Dipolar Electric Field 145 7.2.1 Experimental Setup ................. 145 7.2.2 Large-Area Filament Reconstruction . . . . . . . . 147 7.2.3 One-Dimensional Model of a Large-Area Filament 148 7.2.4 Magnetic Field in the One-Dimensional Model 153 7.2.5 Equal-Areas Rule for Coexistence Field ... 155 7.2.6 Bendable Filament .............. 157 7.3 Filamentary Structure under Interband Illumination 158 7.3.1 Dynamic Behaviour of Illuminated Samples 158 7.3.2 Hypothesis on the Underlying Mechanism 162 7.3.3 Large Time Scale Dynamic Behaviour 165 7.4 Conclusions..................... 166 x Table of Contents 8 Spatiotemporal Patterns and Generic Bifurcations in a Semicon ductor Device by F.-I. Niedernostheide 168 8.1 Introduction.............................. 168 8.2 Measuring Techniques . . . . . . . . . . . . . . . . . . . . . . . . 170 8.3 Experimentally Observed Bifurcation Sequences by Increasing the DC Voltage Bias . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 8.3.1 The Current-Voltage Characteristic . . . . . . . . . . . . 172 8.3.2 Transition of a Spatially Uniform State to a Static Local- ized Filament . . . . . . . . . . . . . . . . . . . . . . . . . 172 8.3.3 Transition of a Static to a Rocking Filament ....... 174 8.3.4 Period-Doubling Cascade and Chaotic Filament Motions. 175 8.3.5 Transition of a Rocking to a Travelling Filament . . 177 8.4 Influence of Other Parameters on the Dynamical Behaviour 179 8.4.1 Frequency-Locking and Quasiperiodicity . 179 8.4.2 Influence of the Temperature 181 8.4.3 Influence of a Magnetic Field 182 8.5 Model and Physical Mechanism . . . 183 8.5.1 Two-Layer Model. . . . . . . 183 8.5.2 Activation, Inhibition, Competition 186 8.6 Numerical Results .............. 187 8.6.1 Bifurcations to Static, Breathing, Travelling and Chaot- ically Oscillating Filaments by Using Homogeneous Neu mann Boundary Conditions . . . . . . . . . . . . . . . . . 188 8.6.2 Influence of the Time Constants .............. 194 8.6.3 Bifurcations to Static, Rocking and Travelling Filaments by Using Mixed Boundary Conditions 194 8.7 Summary and Conclusions. . . . . . . . . . . . . . . . . . . . . . 197 9 Current Filamentation in P-I-N Diodes: Experimental Observations and an Equivalent Circuit Model· by R. Symanczylc 200 9.1 Introduction................. 200 9.2 Theoretical Description .......... 202 9.2.1 Double Injection with Deep Traps 202 9.2.2 Equivalent Circuit Model 204 9.3 Stationary Pattern Formation .... . 206 9.3.1 Experimental Technique ... . 207 9.3.2 Observations and Comparison. 208 9.4 Spatio-Temporal Dynamics .. . 211 9.4.1 Periodic Oscillations .. . 212 9.4.2 Nonperiodic Oscillations. 214 9.5 Conclusion ........... . 216
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