Quantum Dots:Fundamentals, Applications, and Frontiers NATO Science Series A Series presenting the results of scientific meetings supported under the NAAATO Science Programme. The Series is published by IOS Press, Amsterdam, and Springer (formerly Kluwer Academic Publishers) in conjunction with the NATO Public Diplomacy Division. Sub-Series I. Life and Behavioural Sciences IOS Press II. Mathematics,Physics and Chemistry Springer (formerly Kluwer Academic Publishers) III.Computer and Systems Science IOS Press IV.Earth and Environmental Sciences Springer (formerly Kluwer Academic Publishers) The NATO Science Series continues the series of books published formerly as the NATO ASI Series. The NATO Science Programme offers support for collaboration in civil science between scientists of countries of the Euro-Atlantic Partnership Council.The types of scientific meeting generally supported are “Advanced Study Institutes”and “Advanced Research Workshops”, and the NATO Science Series collects together the results of these meetings.The meetings are co-organized by scientists from , NATO countries and scientists from NATOs Partner countries – countries of the CIS and Central and Eastern Europe. Advanced Study Institutesare high-level tutorial courses offering in-depth study of latest advances in a field. Advanced Research Workshops are expert meetings aimed at critical assessment of a field, and identification of directions for future action. As a consequence of the restructuring of the NATO Science Programme in 1999, the NATO Science Series was re-organized to the four sub-series noted above. Please consult the following web sites for information on previous volumes published in the Series. http://www.nato.int/science http://www.springeronline.com http://www.iospress.nl Series II:Mathematics,Physics and Chemistry – Vol.190 Quantum Dots: Fundamentals, Applications, and Frontiers edited by Bruce A.Joyce The Blackett Laboratory, Imperial College London, U.K. Pantelis C.Kelires Physics Department, University of Crete, Heraclion, Crete, Greece and Foundation for Research and Technology-Hellas (FORTH), Heraclion, Crete, Greece Anton G.Naumovets National Academy of Sciences of Ukraine, Institute of Physics, Kiev, Ukraine and Dimitri D. Vvedensky The Blackett Laboratory, Imperial College London, U.K. “British Association of Crystal Growth” Published in cooperation with NATO Public Diplomacy Division Proceedings of the NATO Advanced Research Workshop on Quantum Dots:Fundamentals, Applications and Frontiers Crete, Greece , 20 24 July 2003 A C.I.P.Catalogue record for this book is available from the Library of Congress. ISBN 10 1-4020-3314-1 (PB) Springer Dordrecht, Berlin, Heidelberg, New York ISBN 13 978-1-4020-3314-8 (PB) Springer Dordrecht, Berlin, Heidelberg, New York ISBN 10 1-4020-3313-3 (HB) Springer Dordrecht, Berlin, Heidelberg, New York ISBN 10 1-4020-3315-X (e-book) Springer Dordrecht, Berlin, Heidelberg, New York ISBN 13 978-1-4020-3314-1 (HB) Springer Dordrecht, Berlin, Heidelberg, New York ISBN 13 978-1-4020-3314-5 (e-book) Springer Dordrecht, Berlin, Heidelberg, New York Published by Springer, P.O.Box 17, 3300 AADordrecht, The Netherlands. Printed on acid-free paper All Rights Reserved © 2005 Springer No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Printed in the Netherlands. CONTENTS Preface ix List of Contributors xi Atomistic Processes during Quantum Dot Formation QuantumDotsintheInAs/GaAsSystem:AnOverviewoftheirFormation 1 B.A.JoyceandD.D.Vvedensky First-PrinciplesStudyofInAs/GaAs(001)Heteroepitaxy 27 E.PenevandP.Kratzer FormationofTwo-DimensionalSi/GeNanostructuresObservedbySTM 43 B.Voigtla¨¨nder Diffusion,NucleationandGrowthonMetalSurfaces 55 O.Biham,I.Furman,H. Mehl andJ.F.Wendelken The Stranski–Krastanov Transition 71 TheMechanismoftheStranski–KrastanovTransition A.G.Cullis,D.J.Norris,T.Walther,M.A.Migliorato,andM.Hopkinson Off-latticeKMCSimulationsofStranski-Krastanov-LikeGrowth 89 M.BiehlandF.Much TemperatureRegimesofStrain-InducedInAsQuantumDotFormation 103 C.HeynandA.Bolz KineticModellingofStrainedFilms: EffectsofWettingandFacetting 121 D.KandelandH.R.Eisenberg Ge/SiNanostructureswithQuantumDotsgrownbyIon-Beam-Assisted 135 Heteroepitaxy A.V.Dvurechenskii,J.V.Smagina,V.A.Armbrister,V.A.Zinovyev, P.L.Novikov,S.A.Teys,andR.Groetzschel v vi Self-Assembly of Quantum Dot Arrays LateralOrganizationofQuantumDotsonaPatternedSubstrate 145 C.Priester SomeThermodynamicAspectsofSelf-Assemblyof Quantum Dot 157 Arrays J.E.PrietoandI.Markov TheSearchforMaterialswithSelf-AssemblingProperties: TheCaseof 173 Si-basedNanostructures I.Goldfarb Structure and Composition of Quantum Dots X-RayScatteringMethodsfortheStudyofEpitaxialSelf-Assembled 183 QuantumDots J.Stangl,T.Schu¨¨lli,A.Hesse,G.Bauer,andV.Holy´ Carbon-InducedGeDotsonSi(100): InterplayofStrainandChemical 209 Effects G.Hadjisavvas,Ph. Sonnet,andP.C.Kelires GrowthInformationCarriedbyReflectionHigh-EnergyElectron 221 Diffraction A´. Nemcsics Electrons and Holes in Quantum Dots EfficientCalculationofElectronStatesinSelf-AssembledQuantum 239 Dots: ApplicationtoAugerRelaxation D.Chaney,M.Roy,andP.A.Maksym QuantumDotMoleculesandChains 257 W.Jasko´lski,M.Zielin´´ski,A.Stro´´z˙ecka,G.W.Bryant,andJ.Aizpurua CollectivePropertiesofElectronsandHolesinCoupledQuantumDots 269 G.Goldoni,F.Troiani,M.Rontani,D.Bellucci,E.Molinari,and U.Hohenester vii PhaseTransitionsinWignerMolecules 285 J.Adamowski,B.Szafran,andS.Bednarek FastControlofQuantumStatesinQuantumDots: Limitsdueto 301 Decoherence L.Jacak,P.Machnikowski,andJ.Krasnyj Optical Properties of Quantum Dots RealSpaceAbInitioCalculationsofExcitationEnergiesinSmall 317 SiliconQuantumDots A.D.Zdetsis,C.S.Garoufalis,andS.Grimme GeSi/Si(001)StructureswithSelf-AssembledIslands: Growthand 333 OpticalProperties N.V.Vostokov,Yu. N.Drozdov,D.N.Lobanov,A.V.Novikov, M.V.Shaleev,A.N.Yablonskii,Z.F.Krasilnik,A.N.Ankudinov, M.S.Dunaevskii,A.N.Titkov,P.Lytvyn,V.U.Yukhymchuk,and M.Ya. Valakh QuantumDotsinHighElectricFields: FieldandPhotofieldEmission 353 fromGeNanoclustersonSi(100) A.A.Dadykin,A.G.Naumovets,Yu. N.Kozyrev,M.Yu. Rubezhanska, andYu. M.Litvin OpticalEmissionBehaviorofSiQuantumDots 369 X.ZianniandA.G.Nassiopoulou Strain-DrivenPhenomenauponOvergrowthofQuantumDots: 377 ActivatedSpinodalDecompositionandDefectReduction M.V.MaximovandN.N.Ledentsov Preface The morphology that results during the growth of a material on the substrate of a different material is central to the fabrication of all quantum heterostructures. Thismorphologyisdeterminedbyseveralfactors,includingthemannerinwhich strain is accommodated if the materials have different lattice constants. One of themosttopicalmanifestationsoflatticemisfitistheformationofcoherentthree- dimensional(3D)islandsduringtheStranski–Krastanovgrowthofahighly-strained system. TheprototypicalcasesareInAsonGaAs(001)andGeonSi(001),though othermaterialscombinationsalsoexhibitthisphenomenon. Whenthe3Dislands are embedded within epitaxial layers of a material that has a wider band gap, the carrierswithintheislandsareconfinedbythepotentialbarriersthatsurroundeach island,forminganarrayofquantumdots(QDs). Suchstructureshavebeenproducedforbothbasicphysicsstudiesanddevicefabri- cation,includingQDlasersandlight-emittingdiodes(LEDs)operatingatthecom- mercially important wavelengths of 1.3 µm and 1.55 µm. On a more speculative level,QDensembleshavebeensuggestedasapossiblepathwayforthesolid-state implementationofaquantumcomputer. Althoughsomeoftheprinciplesofquan- tumcomputinghavebeenverifiedbyothermeans, thepracticalutilizationofthis newcomputing paradigm may warrant some sortof solid state architecture. QDs areseenaspossiblecomponentsofsuchacomputer,asevidencedbyanumberof papersappearingintheliteratureproposingQD-basedarchitecturesandworkshops thatarebeingorganizedtoexplorethesepossibilities. Inviewofmanydevelopmentsonseveralfronts,aworkshoptobringtogetherex- perimentalistsandtheoristsfromvariousdisciplinestostimulateinterdisciplinary cross-fertilization,toreviewrecentprogressandremainingchallenges,andtodis- cusscommonproblemsandsolutions,wasviewedasbeingparticularlytimely. The ScientificAffairsDivisionofNATO,underitsAdvancedResearchWorkshoppro- gram,andtheBritishAssociationofCrystalGrowth,kindlyagreedtosupportsuch ameeting. Entitled“QuantumDots:Fundamentals, Applications, andFrontiers”, thisARWwasheldattheSantaMarinaBeachHotelinAmmoudara,Cretebetween 20–24July,2003. Thethemeswerethefundamentalsofthegrowth,structure,and propertiesofquantumdots,theirapplicationsindevices,andtheirpossiblefuture uses. Themainemphasiswastheidentificationofthefactorsthatlimittheutiliza- tionofquantumdotsinapplicationsandpossiblestrategiesbywhichthesecanbe overcome. ThisARWhighlightedthefollowingkeyissues: ix x • ThemechanismofquantumdotformationduringStranski–Krastanovgrowth isacomplexprocess,withmanykeyfactorsthatarestillnotcompletelyunder- stoodattheatomisticlevel,includingtheformationkinetics,themorphological evolutionofdots(“precursors”and“pyramids”), andchangescausedbycap- ping. • The role of atomistic and continuum modelling is becoming increasingly im- portantinaddressingtheseissues,withseveralspeakersdescribingmodelsthat reproduceseveralimportantaspectsofStranski–Krastanovgrowth. • Therearetheoreticalandcomputationtoolsavailabletodeterminetheelectronic propertiesofquantumdots,butthedependenceonshapeandcompositionoften inhibitstheabilitytoreachunequivocalconclusions. • Despitetheexperimentaluncertaintiesaboutfundamentalsteps,thecontrolled growthofquantum dotsisalready leading toanumberofpromising applica- tions,includinglasersandsingle-photondetectors. • Quantumcomputingbasedonaquantumdotarchitectureisapossibility,even if confined to low temperatures, with the scalability and large confinement energiesbeingparticularlyattractivefeatures. Fordetrimentaleffects,suchas decoherenceduetophonons,plausiblesolutionshavebeenproposed. Thepresentvolumecontainstheproceedingsofthisstimulatingmeeting. The organizers are deeply thankful to the Scientific Affairs Committee of NATO and the British Association of Crystal Growth for their sponsorship and enthusiastic endorsementofthismeeting. BruceA.Joyce PantelisC.Kelires AntonG.Naumovets DimitriD.Vvedensky