Materials for Tomorrow: Theory, Experiments and Modelling PDF
Preview Materials for Tomorrow: Theory, Experiments and Modelling
SpringerSeriesin materials science 93 SpringerSeriesin materials science Editors: R.Hull R.M.Osgood,Jr. J.Parisi H.Warlimont The Springer Series in Materials Science covers the complete spectrum of materials physics, includingfundamentalprinciples,physicalproperties,materialstheoryanddesign.Recognizing theincreasingimportanceofmaterialsscienceinfuturedevicetechnologies,thebooktitlesinthis seriesreflectthestate-of-the-artinunderstandingandcontrollingthestructureandproperties ofallimportantclassesofmaterials. 76 SpirallyAnisotropicComposites 85 LifetimeSpectroscopy ByG.E.Freger,V.N.Kestelman, AMethodofDefectCharacterization andD.G.Freger inSiliconforPhotovoltaicApplications ByS.Rein 77 ImpuritiesConfined inQuantumStructures 86 Wide-GapChalcopyrites ByP.O.HoltzandQ.X.Zhao Editors:S.SiebentrittandU.Rau 78 MacromolecularNanostructured 87 Micro-andNanostructuredGlasses Materials ByD.Hülsenberg,A.Harnisch, Editors:N.UeyamaandA.Harada andA.Bismarck 79 MagnetismandStructure 88 IntroductiontoWaveScattering, inFunctionalMaterials LocalizationandMesoscopicPhenomena Editors:A.Planes,L.Mano˜sa, ByP.Sheng andA.Saxena 89 Magnetoscience 80 IonImplantation MagneticFieldEffectsonMaterials: andSynthesisofMaterials FundamentalsandApplications ByM.NastasiandJ.W.Mayer Editors:M.YamaguchiandY.Tanimoto 81 MetallopolymerNanocomposites 90 InternalFrictioninMetallicMaterials ByA.D.PomogailoandV.N.Kestelman AReferenceBook ByM.S.Blanter 82 PlasticsforCorrosionInhibition ByV.A.Goldade,L.S.Pinchuk, 91 Time-dependentMechanicalProperties A.V.MakarevichandV.N.Kestelman ofSolidBodies ATheoreticalApproach 83 SpectroscopicProperties ofRareEarths ByW.Gräfe inOpticalMaterials Editors:G.LiuandB.Jacquier 92 SolderJointTechnology Materials,Properties,andReliability 84 Hartree–Fock–SlaterMethod ByK.N.Tu forMaterialsScience TheDV–XAlphaMethodforDesign 93 MaterialsforTomorrow andCharacterizationofMaterials Theory,ExperimentsandModelling Editors:H.Adachi,T.Mukoyama, Editors:S.Gemming,M.Schreiber, andJ.Kawai andJ-B.Suck Volumes25–75arelistedattheendofthebook. · · S. Gemming M. Schreiber J.-B. Suck (Eds.) Materials for Tomorrow Theory, Experiments and Modelling With92Figures,7inColour 123 PDDr.SibylleGemming Prof.Dr.Jens-BoieSuck InstituteofIonBeamPhysics InstituteofPhysics andMaterialsResearch UniversityofTechnologyChemnitz ForschungszentrumDresden-Rossendorfe.V. ReichenhainerStraße70 PF510119 D-09107Chemnitz,Germany D-01314Dresden,Germany E-mail:[email protected] E-Mail:[email protected] Prof.Dr.MichaelSchreiber InstituteofPhysics UniversityofTechnologyChemnitz ReichenhainerStraße70 D-09107Chemnitz,Germany E-mail:[email protected] SeriesEditors: ProfessorRobertHull ProfessorJürgenParisi UniversityofVirginia UniversitätOldenburg,FachbereichPhysik Dept.ofMaterialsScienceandEngineering Abt.Energie-undHalbleiterforschung ThorntonHall Carl-von-Ossietzky-Strasse9–11 Charlottesville,VA22903-2442,USA 26129Oldenburg,Germany ProfessorR.M.Osgood,Jr. ProfessorHansWarlimont MicroelectronicsScienceLaboratory InstitutfürFestkörper- DepartmentofElectricalEngineering undWerkstofforschung, ColumbiaUniversity Helmholtzstrasse20 SeeleyW.MuddBuilding 01069Dresden,Germany NewYork,NY10027,USA LibraryofCongressControlNumber:2006935255 ISBN 978-3-540-47970-3 SpringerBerlinHeidelbergNewYork Thisworkissubjecttocopyright.Allrightsarereserved,whetherthewholeorpartofthematerialisconcerned, specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,broadcasting,reproduction onmicrofilmorinanyotherway,andstorageindatabanks.Duplicationofthispublicationorpartsthereofis permittedonlyundertheprovisionsoftheGermanCopyrightLawofSeptember9,1965,initscurrentversion, andpermissionforusemustalwaysbeobtainedfromSpringer.Violationsareliabletoprosecutionunderthe GermanCopyrightLaw. SpringerisapartofSpringerScience+BusinessMedia. springer.com ©Springer-VerlagBerlinHeidelberg2007 Theuseofgeneraldescriptivenames,registerednames,trademarks,etc.inthispublicationdoesnotimply, evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfromtherelevantprotectivelawsand regulationsandthereforefreeforgeneraluse. Typesetting:Digitaldatasuppliedbyeditors Production:LE-TEXJelonek,Schmidt&VöcklerGbR,Heidelberg,Germany Coverproduction:WMXDesignGmbH,Heidelberg Printedonacid-freepaper SPIN:11874423 57/3100/YL 543210 Preface Materials science has assumed a key position for new technological devel- opments, and is therefore strongly supported by industry and governments. Nowadays it occupies a bridging position between physics, chemistry and en- gineering and extends from basic science in physics and chemistry on the atomic scale to large-scale applications in industry. The increasing number of materials science study courses at universities underlines the present and future importance of understanding and developing materials for the future. The contributions to this book evolved from the lectures of such a course, namely the Heraeus summer school on “New Materials for Today, Tomorrow and Beyond”, held at Chemnitz University of Technology in October 2004. Looking at the rapidly developing communications industry, it is obvious that a large part of current research for future materials is devoted to the understanding of materials to be used in nanometer (nm) scale devices. It is therefore not surprising that five of the six lectures collected in this volume aredevotedmoreorlessdirectlytothenmscale,whilethefirstonetreatsone ofthecentralunsolvedproblemsofcondensedmatterphysicsand–becauseof thewidespreadindustrialapplicationofglassesineverydaylife–touchingalso materialsscience.Someofthematerialsdiscussedherearealreadyusedtoday, for others the development has proceeded far enough that their application can be expected in the near future. Yet others,however,we will not be ready to use until some years from now, assuming that the difficulties connected with their application are solved in the near future. Theabove-mentionedfirstarticle,writtenby oneofthe bestknownscien- tists in the field of computer simulations, introduces the molecular dynamics (MD) methods used in the calculation of the structure and atomic-scale dy- namicsofnewmaterials.Themethodhasnowgainedanadmirablepredictive power in materials science, explaining details not or hardly accessible by ex- periments. This has become possible through ab initio calculations of the electronic structure of the material using density functional theory (DFT), which provide very realistic results. These can then be used to model the force field, in which the atoms interact, for MD simulation of larger systems. VI Preface In this way undercooled silicate-based fluids and glasses have been success- fully investigated including the as yet poorly understood transition from the fluid to the glassy phase. The same kind of technique was also used to investigate inorganic nano- tubes. Carbonnanotubes (NT) have been at the centre of interest since their discovery in 1991, followed by organic NT BxCyNz. Both of them are al- ready used in many applications and will find more in the future. However, since then dozens of other inorganic materials have been discovered, which form NT as well. The starting materials are layered compounds, character- ized by strong covalent bonds within the layers and van-der-Waals forces be- tweenthem.Theirstructureisoftencomplicatedandtheirpropertiesnotwell known, even though they have great application potential. Simulations of in- organicNTarethereforepresentedinthe secondcontribution,withaviewto better understanding the properties of these special NT. Nanotechnologyalsoplaysa decisiveroleininformationtechnology.How- ever,therapidincrease(doublingoftheInternettrafficevery6months,ofthe wireless capacities every 9 months and of the magnetic information storage every15months)cannotbecompensatedbyacorrespondingshrinkageofthe semiconductordevices,asitwasachievedinthepast30years.Tokeepupwith the demands, completely new devices have to be invented, operating on the nanoscaleandexploitingquantumeffects.Onepossibilityis tousethespinof the electron in addition to its charge for information transmission and stor- age, i.e. going from conventional electronics to spintronics. The foundations of this technique, exploiting the giant magnetoresistance and the tunneling magnetoresistance are discussed from the experimental and theoretical point of view in the third contribution. Interfaces play a very important role for the stability and functioning of materials, sometimes as barriers, sometimes mediating between adjacent grains or layers, sometimes protecting the material next to them, avoiding overheatingorcorrosionineverydaymaterials.Homophase(betweentwoma- terials of the same chemical composition and atomic structure) grain bound- aries (GB) and heterophase (between two chemically or structurally different materials) interfaces are discussed from a theoretical point of view in the fourth contribution. Electronic and atomic structures at planar GB and het- erophase interfaces are investigated and classified according to the dominant interaction determining their properties. For many technical applications,the dimensions of semiconductor devices are rapidly approachinglength scales at which a classical description of their electronic structure and transport properties is insufficient and quantum ef- fects must be taken into account. But since these devices are still too large foranatomisticdescription,continuummodelswithempiricallyadjustedma- terial parameters are successfully used to describe their properties. These continuum models and their implementation in a simulation software are de- scribed in the fifth contribution. Preface VII When working with devices on the nanoscale one necessarily runs into theproblemthatsomephysicallysignificantlengths,likeacorrelationlength, a screening length, the mean free path, etc. start to exceed the dimension of the devices. This necessarily leads to a drastic change of the physical proper- ties in comparison to those in the same material at larger dimensions. Such achangeofpropertieswithrespecttothemeltingtemperature,magneticand mechanical properties and finally to the atomic dynamics is discussed at the example of metallic nanocrystals in the final contribution to this book. As the lectures were given to students of different disciplines (physics, chemistry,materialsscience),thearticlesdescribenotonlyourcurrentknowl- edge in eachof the fields, but also basic facts needed for their understanding. Thus the articles combine basic information at a textbook level with a pre- sentation of cutting-edge research in the field and an outlook to future de- velopments, thereby bridging the gap between specialized reviews and study books.Inaddition,lecturesonmaterialssimulation,averyrapidlyadvancing discipline, are combined with lectures on experimental research in materials science, and the techniques used in both of these disciplines. Theeditorsofthisbookareindebtedtothelecturersofthesummerschool for taking on the burden of writing up their contributions in addition to presentingthem. Finallywe wouldlike to thank the WE HeraeusStiftung for enabling us to organize this school by its generous financial support. Chemnitz, July 2006 Sibylle Gemming Michael Schreiber Jens-Boie Suck Contents 1 Computer Simulations of Undercooled Fluids and Glasses K. Binder, D. Herzbach, J. Horbach, M.H. Mu¨ser.................... 1 1.1 Introduction ............................................... 1 1.2 A Tutorial Review of the MD Technique....................... 4 1.2.1 The Verlet Algorithm ................................ 4 1.2.2 How to Estimate Intensive Thermodynamic Variables from Microcanonical MD Runs; Realization of Other Ensembles ....................... 7 1.2.3 Diffusion, Hydrodynamic Slowing Down, Einstein and Green–Kubo Relations ........................... 9 1.3 A Comparative Test of Model Potentials for Silica .............. 12 1.4 Simulations of Molten and Glassy Silicon Dioxide............... 23 1.5 Mixtures of Silicon Dioxide with Sodium Oxide and Aluminium Oxide....................................... 27 1.6 Conclusions................................................ 29 References ...................................................... 30 2 Simulation of Inorganic Nanotubes A.N. Enyashin, S. Gemming, G. Seifert ............................ 33 2.1 Introduction ............................................... 33 2.2 Design of Inorganic Nanotubes ............................... 34 2.3 General Criteria for the Stability of Inorganic Nanotubes ........ 38 2.4 Theoretical Prediction of the Properties of Non-Carbon Nanotubes ................................... 40 2.4.1 Nanotubes of the IVA Group Elements ................. 41 2.4.2 Nanotubes of the VA Group Elements.................. 43 2.4.3 Nanotubes of Boron and Borides ...................... 43 2.4.4 Nanotubes of Boron Nitride and its Analogues .......... 45 X Contents 2.4.5 Nanotubes of Chalcogenides .......................... 47 2.4.6 Nanotubes of Oxides................................. 50 2.5 Conclusion................................................. 54 References ...................................................... 55 3 Spintronics: Transport Phenomena in Magnetic Nanostructures P. Zahn ........................................................ 59 3.1 Introduction ............................................... 59 3.2 Magnetism in Nanostructures ................................ 61 3.2.1 Magnetism in Reduced Dimensions .................... 61 3.2.2 First Principals Calculational Scheme .................. 62 3.2.3 Magnetic Interlayer Exchange Coupling ................ 64 3.3 Transport Phenomena....................................... 66 3.3.1 Transport Theory ................................... 66 Diffusive and Coherent Transport Regime............... 67 Boltzmann Theory................................... 68 Residual Resistivity.................................. 69 Landauer Theory.................................... 70 3.3.2 Giant Magnetoresistance ............................. 72 Basics.............................................. 72 Microscopic Origin................................... 73 Applications ........................................ 77 3.3.3 Tunneling Magnetoresistance.......................... 78 Basics.............................................. 78 Microscopic Origin................................... 80 Applications ........................................ 85 References ...................................................... 86 4 Theoretical Investigation of Interfaces S. Gemming, M. Schreiber ........................................ 91 4.1 Interfaces – Boundaries Between Two Phases................... 91 4.1.1 Introduction ........................................ 92 4.1.2 Interactions......................................... 95 Coulomb Interaction ................................. 95 Elastic Interaction ................................... 96 Electron Transfer.................................... 97 Pauli Repulsion ..................................... 98 Image Charge Interaction............................. 98 4.2 Theoretical Methods ........................................ 98 4.2.1 Theory of the Electronic Structure..................... 99 Density-Functional Theory............................ 99 Computational Details of Bulk State Calculations .......100 Density-Functional Tight-Binding Approaches ..........100 Contents XI 4.2.2 Classical Modelling ..................................101 Image-Charge Models ................................101 Effective Many-Body Potentials .......................102 Ionic Models ........................................103 4.3 Homophase Boundaries......................................104 4.3.1 Pristine Boundaries..................................105 4.3.2 Non-Stoichiometric and Doped Boundaries..............108 4.4 Heterophase Boundaries .....................................109 4.4.1 Wetting and Growth of Metal Layers...................110 4.4.2 Metal–Ceramic Boundaries ...........................112 4.4.3 Reactive Metal–Semiconductor Interfaces ...............116 4.5 Summary and Outlook ......................................118 References ......................................................119 5 Electronic Structure and Transport for Nanoscale Device Simulation A. Trellakis, P. Vogl..............................................123 5.1 Introduction ...............................................123 5.2 Electronic Structure of Semiconductors........................125 5.2.1 Bloch Theory and the Band Structure..................125 5.2.2 The k·p-Approximation ..............................127 5.2.3 Conduction and Valence Band Models..................128 5.3 Heterostructures............................................130 5.3.1 The Envelope Function Approximation.................130 5.3.2 Elastic Deformation and Strain........................131 5.3.3 Carrier Densities at Non-Zero Temperature .............132 5.3.4 Charge Distributions and the Poisson Equation..........134 5.4 Carrier Transport in Nanostructures ..........................135 5.4.1 Classical Ballistic Transport ..........................135 5.4.2 Scattering and the Boltzmann Equation ................136 5.4.3 The Drift-Diffusion Equations.........................138 5.4.4 Quantum Corrected Drift-Diffusion ....................139 5.4.5 Quantum Ballistic Transport..........................140 5.5 The nextnano3 Simulation Package ...........................141 5.5.1 Capabilities Overview ................................141 5.5.2 Numerical Methods ..................................142 5.5.3 Example Application.................................144 References ......................................................145 6 Metallic Nanocrystals and Their Dynamical Properties Jens-Boie Suck ..................................................147 6.1 Introduction ...............................................147 6.2 Production of Nanocrystalline Materials .......................150 6.3 Characterization of Nanocrystalline Materials ..................155
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