复旦纳米材料和功能器件课件01导论

纳米材料与功能器件IntroductiontoNanomaterialsandFunctionalDevices郑耿锋Fall20182WhatisNANO?纳米材料：基本单元的颗粒或晶粒尺寸至少在一维上小于100nm，且必须具有与常规材料截然不同的光、电、热、化学或力学性能的一类材料体系。纳米SnO2镀层纳米碳黑粒子纳米Au,Ag粒子?3Nano=Onebillionthofsomething4IntroductiontoNanomaterials&Nanotechnology“Thereisplentyofroomatthebottom…”–RichardFeynman,1959Feynman以“由下而上的方法（Bottom-Up）”出发，提出从单个分子甚至原子开始进行组装，以达到设计要求——“至少依我看来，物理学的规律不排除一个原子一个原子地制造物品的可能性。”并预言，“当我们对细微尺寸的物体加以控制的话，将极大得扩充我们获得物性的范围。”51-D,2-D,and3-D(0-D)•纳米材料是指在三维空间中至少有一维处于纳米尺度范围或由它们作为基本单元构成的材料。按维度，纳米材料的基本单元可分为三类：零维，一维，二维。因为这些单元具有量子性质，因此又称为：量子点，量子线和量子阱(Quantumdot,Quantumwire,Quantumwell)。6NanostructureinNature7WhyStudyNanomaterials&NanotechnologyElectronics/CommunicationBiology/MedicineRenewableEnergyWater/FoodBiomimeticsDoSmall,ThinkBig.8第二部分：光学显微镜与电子显微镜•纳米材料结构表征与器件制备（一）：光学显微镜与电子显微镜–显微技术原理–光学显微镜–透射电子显微镜–扫描电子显微镜–能量损失谱与元素分析9LensandImagingSystem•Lensesarethecentralcomponentofanimagingsystem.•Multiplelenssetsareusedinacomplexmicroscopetoprovidehighmagnificationandresolution.10MagnificationandResolution•Magnification:thelenscapacitytoexpandanimage•Resolution:thesmallestpixelcanbespatiallydifferentiatedfromitsclosestneighbors11TheoreticalResolutionLimitforOpticalSystem•TheoreticalResolutionLimit:isdeterminedbythewavelengthoflightusedforimagingλ/2•Wavelengthof“light”:–Opticalmicroscope(visiblelight):λ=400—600nm–SEM(1—10kVacceleratingvoltage):λ=1.1×10-11m(11pm)–TEM(100—200kVacceleratingvoltage):λ=3.6×10-12m(3.6pm)12Aberrations•SphericalAberration（球差）:–duetothefocuspowerdifferencebetweenlenscenterandedges13Aberrations•ChromaticAberration（色差）:–duetothedifferencerefractiveindicesfordifferentwavelengths(colors),(recalln=c/λ)14Aberrations•StigmatismAberration（像散）:–duetotheasymmetryofalensinthex-andy-directions15PracticalResolution•Wavelengthof“light”:(recallλ=h/P)–Opticalmicroscope(visiblelight):λ=400—600nm–SEM(1—10kVacceleratingvoltage):λ=1.1×10-11m(11pm)–TEM(100—200kVacceleratingvoltage):λ=3.6×10-12m(3.6pm)•Practicalresolution–Opticalmicroscope:λ=300—600nm–SEM(1—10kVacceleratingvoltage):λ=2—10nm–TEM(100—200kVacceleratingvoltage):λ=0.1—1nm16Optical(Light)Microscope17IlluminationSourceLaserSpectrum18NumericalAperture（N.A.,数值孔径）•N.A.=nsinα•ThehigherN.A.oftheobjectivelens,thebetterresolution.•MethodstoimprovetheN.A.ofanobjectivelens.19BrightFieldandDarkFieldImaging•DarkfieldcanimproveContrast,notresolution!20ConfocalFluorescenceMicroscope21FluorescenceLightPath22TransmissionElectronMicroscope1932:firstTEMbyE.Ruska(Germany)1986:Nobelphysicsprize组成部分：照明系统、成像系统、记录系统、真空系统、电气系统23WorkingPrinciple•工作原理–成像原理与光学显微镜类似。–它们的根本不同点在于光学显微镜以可见光作照明束，透射电子显微镜则以电子为照明束。在光学显微镜中将可见光聚焦成像的是玻璃透镜，在电子显微镜中相应的为磁透镜。–由于电子波长极短，同时与物质作用遵从布拉格（Bragg）方程，产生衍射现象，使得透射电镜自身在具有高的像分辨本领的同时兼有结构分析的功能。TEMimageofanE.coli2425HotElectronGunandFieldEmissionGunHotElectronGunFieldEmissionGun26ElectromagneticLens,Apertures•Electromagneticlens–Thefocusingstrengthcanbetunedbyadjustingthemagnetizing/excitingcurrent（激磁电流）.–Over-focus（过焦）andunder-focus（欠焦）.•IlluminationSystem–Highvacuum(~10-6Torr)–Condenserlens1&2–Obtainhighlycollimatedanduniformelectronbeam27ElectronDiffractioninTEMλλLλLλRddLRLKLsin2sin22sin2tg22tg的乘积为一常数：和值确定，速电压一定时，为衍射相机长度，当加式。这就是电子衍射基本公，得：代入布拉格公式很小，所以子衍射的由于电子波长很短，电K为相机常数。如果K值已知，即可由衍射斑点的R值计算出晶面组d值：RKRLd28BeamPathsinTEMforImagingandDiffraction•TEMBeamAlignment:–Beamalignment(fromtoptodown)–Abbreviationcorrectionofalllens(themostcriticalone:objectivelens)–Adjustsampleeucentricheight•Backfocalplane(fortheobjectiveaperture)•Selectedareaelectrondiffraction(SAED)aperture29ImageandElectronDiffractionPatternofCrystalsPolycrystalSingleCrystalImageDiffraction3031Example:DirectKineticsObservationinsideTEMObservationofSinanowiregrowthbyAunanoparticlecatalyzedVapor-solid-liquidmechanisminsideTEM—YangPD,JACS,2001,123,3165.Observationoffullerenesmovementandrotationinsideasingle-wallcarbonnanotubebyTEM—IijimaS.,NanoLetters,2007,7,3704.32ScanningElectronMicroscope(SEM)Advantages:•Highmagnification(upto100kX)•Highresolution(upto1nm)•Largefieldofview•3Dimaging(althoughlessz-resolution)•Simplesamplepreparation•Possibleforlowvacuumandliveorganismimaging(EnvironmentalSEM,E-SEM)•Energydispersivespectrum(EDS)•Usedasnanoscalefabricationtools:e.g.Electronbeamlithography(EBL),focus-ionbeam(FIB)1942:firstSEMwasinvented.33BeamPathofSEM34ExcitationMechanismofSecondaryElectrons电子散射区域二次电子(试样的表面形貌)电子束(0.2～30kV)试样X射线(元素)反射电子(形貌·成份)荧光(化学结合状态)试样吸收电流俄歇电子（元素）35ScanningandDetection试样电子束扫描(X方向)扫描(Y方向)ACRT的电子束CRTL扫描(X方向)扫描(Y方向)DetectorsinsideSEM:•In-lensdetector•Secondaryelectron(SE)detector•Backscatteringelectron(BSE)detector36SomeExamplesofSEMImagesGold-Nicklenanorodarrayssynthesizedbyelectro-deposition37Example:ZnONanostructuresGrownbyCVDWangZL,MaterialsToday,2004,6,26-33.38EnergyDispersiveX-raySpectroscopy(EDX)EDX(usedinSEMandTEM):•Directanalysisofelementaldistributionofmaterialsinnanoscale.•Principle:basedonworkfunctionofacertainelement.39第三部分：扫描探针显微技术•纳米材料结构表征与器件制备（二）：扫描探针显微技术–原子力显微镜–扫描隧道显微镜–基于扫描探针技术的纳米材料与结构的合成40ScanningProbeMicroscopy(SPM)•AtomicForceMicroscopy(AFM)–ElectrostaticForceMi