Quantum Kinetic Theory and Applications Electrons, Photons, Phonons Quantum Kinetic Theory and Applications Electrons, Photons, Phonons FEDIR T. VASKO OLEG E. RAICHEV Institute of Semiconductor Physics NAS of Ukraine, Kiev Fedir T.Vasko Oleg E.Raichev Institute of Semiconductor Physics,NAS Institute of Semiconductor Physics,NAS 45 Prospekt Nauki 45 Prospekt Nauki Kiev 03028 Ukraine Kiev 03028 Ukraine Library ofCongress Control Number:2005926337 ISBN-10:0-387-26028-5 e-ISBN:0-387-28041-3 ISBN-13:978-0387-26028-0 Printed on acid-free paper. ©2005 Springer Science+Business Media,Inc. All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, Inc., 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis.Use in connection with any form ofinformation storage and retrieval,electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed isforbidden. The use in this publication oftrade names,trademarks,service marks and similar terms,even ifthey are not identified as such,is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. Printed in the United States ofAmerica. (HAM) 9 8 7 6 5 4 3 2 1 springeronline.com Preface Physicalkineticsisthefinalsectionofthecourseoftheoreticalphysics in its standard presentation. It stays at the boundary between gen- eral theories and their applications (solid state theory, theory of gases, plasma, and so on), because the treatment of kinetic phenomena always depends on specific structural features of materials. On the other hand, the physical kinetics as a part of the quantum theory of macroscopic systems is far from being complete. A number of its fundamental is- sues, such as the problem of irreversibility and mechanisms of chaotic responses, are now attracting considerable attention. Other important sections, for example, kinetic phenomena in disordered and/or strongly non-equilibrium systems and, in particular, phase transitions in these systems, arecurrently under investigation. Thequantumtheory of mea- surements and quantum information processing actively developing in the last decade are based on the quantum kinetic theory. Because a deductive theoretical exposition of the subject is not con- venient, the authors restrict themselves to a lecture-style presentation. Now the physical kinetics seems to be at the stage of development when, according to Newton, studying examples is more instructive than learn- ing rules. In view of these circumstances, the methods of the kinetic theory are presented here not in a general form but as applications for description of specific systems and treatment of particular kinetic phe- nomena. The quantum features of kinetic phenomena can arise for several rea- sons. One naturally meets them in strongly correlated systems, when it is impossible to introduce weakly interacting quasiparticles (for exam- ple, in a non-ideal plasma), or in more complicated conditions, such as in the vicinity of the phase transitions. Next, owing to complexity of the systems like superconductors, ferromagnets, and so on, the manifes- tations of kinetic phenomena change qualitatively. The theoretical con- v vi QUANTUM KINETIC THEORY sideration of these cases can be found in the literature. Another reason for studying quantum features of transport and optical phenomena has emerged in the past decades, in connection with extensive investigation ofkineticphenomenaunderstrongexternalfieldsandinnanostructures. The quantum features of these phenomena follow from non-classical dy- namics of quasiparticles, and these are the cases the present monograph takes care of, apart from consideration of standard problems of quan- tum transport theory. Owing to intensive development of the physics of nanostructures and wide application of strong external (both stationary and time-dependent) fields for studying various properties of solids, the theoretical methods presented herein are of current importance for anal- ysis and interpretation of the experimental results of modern solid state physics. This monograph is addressed to several categories of readers. First, it will be useful for graduate students studying theory. Second, the top- ics we cover should be interesting for postgraduate students of various specializations. Third,theresearcherswhowanttounderstandtheback- ground of modern theoretical issues in more detail can find a number of useful results here. The phenomena we consider involve kinetics of electron, phonon, and photon systems in solids. The dynamical prop- erties and interactions of electrons, phonons, and photons are briefly described in Chapter 1. Further, in Chapters 2−8, we present main the- oretical methods: linear response theory, various kinetic equations for thequasiparticlesunderconsideration, anddiagramtechnique. Thepre- sentation of the key approaches is always accompanied by solutions of concrete problems, to illustrate applications of the theory. The remain- ingchaptersaredevotedtovariousmanifestationsofquantumtransport in solids. The choice of particular topics (their list can be found in the Contents) is determined by their scientific importance and methodolog- ical value. The 268 supplementary problems presented at the end of the chaptersarechosentohelpthereadertostudythematerialofthemono- graph. Focusing our attention on the methodical aspects and discussing a great diversity of kinetic phenomena in line with the guiding principle “a method is more important than a result,” we had to minimize both detailed discussion of physical mechanisms of the phenomena considered and comparison of theoretical results to experimental data. It should be emphasized that the kinetic properties are the impor- tant source of information about the structure of materials, and many peculiarities of the kinetic phenomena are used for device applications. Theseappliedaspectsofphysicalkineticsarenotcoveredindetaileither. However, the methods presented in this monograph provide the theoret- ical background both for analysis of experimental results and for device PREFACE vii simulation. In the recent years, these theoretical methods were applied fortheabove-mentionedpurposessoextensivelythatanycomprehensive review of the literature seems to be impossible in this book. For this reason, we list below only a limited number of relevant monographs and reviews. Fedir T. Vasko Oleg E. Raichev Kiev, December 2004 Monographs: 1. J. M. Ziman, Electrons and Phonons, the Theory of Transport Phenomena in Solids, Oxford University Press, 1960. 2. L.P.KadanoffandG.Baym,QuantumStatisticalMechanics,W.A.Benjamin, Inc., New York, 1962. 3. A. A. Abrikosov, L. P. Gor’kov and I. E. Dzialoszynski, Methods of Quantum Field Theory in Statistical Physics, Prentice-Hall, 1963. 4. S. Fujita, Introduction to Non-Equilibrium Quantum Statistical Mechanics, Saunders, PA, USA, 1966. 5. D. N. Zubarev, Nonequilibrium Statistical Thermodynamics, Consultants Bu- reau, New York, 1974. 6. E.M.Lifshitz and L.P.Pitaevski, Physical Kinetics, Pergamon Press, Oxford, 1981. 7. H.BottgerandV.V.Bryksin,Hopping Conduction in Solids,VCHPublishers, Akademie-Verlag Berlin, 1985. 8. V.L.Gurevich,TransportinPhononSystems(ModernProblemsinCondensed Matter Sciences, Vol. 18), Elsevier Science Ltd., 1988. 9. V.F.GantmakherandY.B.Levinson,Carrier Scattering in Metals and Semi- conductors (Modern Problems in Condensed Matter Sciences, Vol. 19), Elsevier Sci- ence Ltd., 1987. 10. A.A.Abrikosov,Fundamentals of the Theory of Metals,North-Holland,1988. 11. H. Haug and S. W. Koch, Quantum Theory of the Optical and Electronic Properties of Semiconductors, World Scientific, Singapore, 1990. 12. N.N.Bogolubov,Introduction to Quantum Statistical Mechanics,Gordonand Breach, 1992. 13. G. D. Mahan, Many Particle Physics, Plenum, New York, 1993. 14. H. Haug and A.-P. Jauho, Quantum Kinetics in Transport and Optics of Semiconductors, Springer, Berlin, 1997. 15. Y. Imry, Introduction to Mesoscopic Physics, Oxford University Press, 1997. 16. D. K. Ferry and S. M. Goodnick, Transport in Nanostructures, Cambridge University Press, New York, 1997. 17. R. P. Feynmann, Statistical Mechanics, Addison-Wesley, 1998. 18. A. M. Zagoskin, Quantum Theory of Many-Body Systems: Techniques and Applications, Springer-Verlag, New York, 1998. 19. F. T. Vasko and A. V. Kuznetsov, Electron States and Optical Transitions in Semiconductor Heterostructures, Springer, New York, 1998. viii QUANTUM KINETIC THEORY 20. J.Rammer,Quantum Transport Theory(FrontiersinPhysics,Vol. 99),West- view Press, 1998. 21. T. Dittrich, P. H¨anggi, G.-L. Ingold, B. Kramer, G. Sch¨on, and W. Zverger, Quantum Transport and Dissipation, Wiley-VCH, Weinheim, 1998. 22. B.K.Ridley,QuantumProcessesinSemiconductors,OxfordUniversityPress, 1999. 23. D. Bouwmeester, A. Ekert, and A. Zeilinger, The Physics of Quantum Infor- mation, Springer, Berlin, Heidelberg, New York, 2000. Reviews: 1. D. N. Zubarev, Double-Time Green’s Functions, Sov. Phys. - Uspekhi 3, 320 (1960). 2. R. N. Gurzhi and A. P. Kopeliovich, Low-Temperature Electrical Conductivity of Pure Metals, Sov. Phys. - Uspekhi 133, 33 (1981). 3. T.Ando,A.B.Fowler,andF.Stern,ElectronicPropertiesofTwo-Dimensional Systems, Rev. Mod. Phys. 54, 437 (1982). 4. J. Rammer and H. Smith, Quantum Field-Theoretical Methods in Transport Theory of Metals,Rev. Mod. Phys. 58,323(1986);J.Rammer,Quantum Transport Theory of Electrons in Solids: A Single-Particle Approach,Rev. Mod. Phys. 63,781 (1991). 5. G. D. Mahan, Quantum Transport Equation for Electric and Magnetic Fields, Physics Reports 145, 251 (1987). 6. W. R. Frensley, Boundary Conditions for Open Quantum Systems Driven Far from Equilibrium, Rev. Mod. Phys. 62, 745 (1990). 7. B. Kramer and A. MacKinnon, Localization: Theory and Experiment, Rep. Prog. Phys. 56, 1469 (1993). 8. C. H. Henry and R. F. Kazarinov, Quantum Noise in Photonics, Rev. Mod. Phys. 68, 801 (1996). 9. C.W.J.Beenakker,Random-MatrixTheoryofQuantumTransport,Rev. Mod. Phys. 69, 731 (1997). 10. Ya. M. Blanter and M. Buttiker, Shot Noise in Mesoscopic Conductors, Physics Reports 336, 1 (2000). 11. P. Lipavsky, K. Morawetz, and V. Spicka, Kinetic Equation for Strongly In- teracting Dense Fermi Systems, Annales de Physique 26, 1 (2001). Contents Preface v 1. ELEMENTS OF QUANTUM DYNAMICS 1 1. Dynamical Equations 1 2. S-Operator and Probability of Transitions 6 3. Photons in Medium 11 4. Many-Electron System 17 5. Electrons under External Fields 25 6. Long-Wavelength Phonons 35 Problems 46 2. ELECTRON-IMPURITY SYSTEM 51 7. Kinetic Equation for Weak Scattering 51 8. Relaxation Rates and Conductivity 57 9. Quasi-Classical Kinetic Equation 65 10. Multi-Photon Processes 72 11. Balance Equations 79 12. Conductance of Microcontacts 87 Problems 94 3. LINEAR RESPONSE THEORY 99 13. Kubo Formula 99 14. Diagram Technique 107 15. Bethe-Salpeter Equation 115 16. Green’s Function as a Path Integral 123 17. Dispersion of Dielectric Permittivity 130 ix x QUANTUM KINETIC THEORY 18. Interband Absorption under External Fields 139 Problems 147 4. BOSONS INTERACTING WITH ELECTRONS 155 19. Kinetic Equation for Boson Modes 155 20. Spontaneous and Stimulated Radiation 162 21. Phonon Instabilities 169 22. Boson Emission by 2D Electrons 176 Problems 184 5. INTERACTING PHONON SYSTEMS 189 23. Phonon-Phonon Collisions 189 24. Thermal Conductivity of Insulators 197 25. Balance Equations for Phonons 201 26. Relaxation of Long-Wavelength Phonons 207 27. Polaritons and Dielectric Function of Ionic Crystals 215 Problems 224 6. EFFECTS OF ELECTRON-ELECTRON INTERACTION 229 28. Hartree-Fock Approximation 229 29. Shift of Intersubband Resonance 235 30. Exciton Absorption 243 31. Electron-Electron Collision Integral 250 32. Coulomb Drag Between 2D Electrons 256 33. Dynamical Screening 262 Problems 273 7. NON-EQUILIBRIUM ELECTRONS 281 34. Electron-Boson Collision Integral 281 35. Quasi-Isotropic and Streaming Distributions 289 36. Diffusion, Drift, and Energy Balance 299 37. Heating under High-Frequency Field 309 38. Relaxation of Population 321 Problems 331 8. NON-EQUILIBRIUM DIAGRAM TECHNIQUE 341 Contents xi 39. Matrix Green’s Function 341 40. Generalized Kinetic Equation 347 41. General Formulation of NDT 355 42. NDT Formalism for Electron-Boson System 364 43. Weak Localization under External Fields 374 Problems 381 9. KINETICS OF BOUNDED SYSTEMS 391 44. Boundary Conditions at Non-Ideal Surface 391 45. Size-Dependent Conductivity 398 46. Thermal Conductivity of Bounded Insulators 405 47. Electron Relaxation by Near-Surface Phonons 411 Problems 420 10. QUANTUM MAGNETOTRANSPORT 425 48. Method of Iterations 426 49. Green’s Function Approach 434 50. Quasi-Classical Conductivity 443 51. Quantum Hall Effect 452 52. Magnetooptics 465 Problems 476 11. PHOTOEXCITATION 483 53. Photogeneration Rate 483 54. Response to Ultrafast Excitation 490 55. Partially Inverted Electron Distribution 497 56. Photoinduced Interband Hybridization 508 57. Excitation of Coherent Phonons 520 Problems 528 12. BALLISTIC AND HOPPING TRANSPORT 537 58. Quantized Conductance 538 59. One-Dimensional Conductors 549 60. Tunneling Current 562 61. Coulomb Blockade 574 62. Polaronic Transport 585 Problems 596