optical fabrication and optical manipulation of semiconductor nanoparticles

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Optical fabrication and Optical manipulation of semiconductor nanoparticles. Ashida lab. Nawaki Yohei. Introduction Optical fabrication and manipulation Advantage of particles Photo Induced force Resonant force Purpose Previous study My study Experimental setup - PowerPoint PPT Presentation



Optical fabrication and Optical manipulation of semiconductor nanoparticlesAshida lab. Nawaki YoheiContentsIntroductionOptical fabrication and manipulationAdvantage of particlesPhoto Induced forceResonant forcePurposePrevious studyMy studyExperimental setupAblation and ManipulationScanning electric microscopyOptical fabricationTablet of GaNCrystal of GaNOptical manipulationZinc oxideSummary1Ablation and manipulation2IntroductionAblation laserManipulation laserAblationFabrication method of particlesusing laser sputteringManipulationTransporting method by the resonant radiation forceSi substrateLow-dimensional structures3Introduction

DOSDOSDOSDOSEEEEBulkThin filmQuantum wireNano particleenhancement of oscillator strengthPhoto induced force4IntroductionGradient ForceScattering and Absorption pressureOptical axisPhoto induced forceGradient forceScattering and Absorption pressurePhoto induced force: Gradient force: Scat. And abs. pressure: Gradient force5IntroductionThe force pushing objects to the focal pointStabilization pointElectrical gradientGaussian beamScattering and Absorption force6IntroductionThe force arising from the momentum transfer from the lightpowerscatteringabsorptionManipulation in various scale7IntroductionMicroparticleNanoparticleAtom1mm~1nm~1mm~1nmOptical tweezersStructural dependenceNo Structural dependenceLaser coolingNo resonanceresonanceStructural dependenceresonanceorNo resonanceIts difficult for optical manipulation.Energy of applied lightEnergy of exciton levelEnergy of applied light=Energy of exciton levelResonant or Non-resonant light8IntroductionNon resonantResonantResonantResonantEaEnhancement by resonant light9Introduction

Ref: T.Iida and H. Ishihara Phys. Rev. Lett. 90, 057403 (2003)Using resonant lightPhoto induced force is drastically enhanced.Numerical calculation example (CuCl)100 times of gravitational accelerationPrevious study10Purpose

Our group has succeeded manipulation of nanoparticlesWide-gap semiconductorCuClZnOK. Inaba phys.stat.sol. (b)243, No.14, (2006)S. Okamoto master thesis (2011)My study11PurposeGaN bulkGaN particlesManipulated GaN particlesablationmanipulation11Fabrication method12Experimental setupNd:YAGTi:sapphireablation lasermanipulation laserwavelength:525nmpulse duration:10ns SHGwavelength:726nmcryostatSi substratesampleback substratefront substrateVacuum state (300K)Superfluid He state (2K)wavelength:718nmpulse duration:100fs Observation method13Experimental setupElectron beamSecondary electronsampleCharacter X-rayCathode LuminescenceSEM measurementCL measurementEnergy Dispersive X-ray SpectrometryScanning electron microscopeScanning electron microscope: Secondary electron: Cathode luminescence :Character X-ray: XTo analyze elementTo take 2D imageOptical fabrication14Gallium Nitride15AblationGaN: 3.4eVcf. ZnSe, SiC, ZnO, CuClGaN has wide controllable range of bandgapwith ternary crystal semiconductor InN, AlN.0.7eV~6.1eVCrystal growth is difficultBlue- and UV-Light emitting diode and laser

Wide-gap semiconductorTablet of GaN16Ablation

Press!PowderTabletSEM images17Ablation

Ablation conditionsVacuum stateNd:YAG power 0.5mJI could fabricate particles...Element analysis18Ablation

EDS dataGa mapping imageSEM imageNitrogen peak was expected. 19Particles were oxidized.Crystal of GaN20AblationCrystal

Tablets included many impurity.The reason why is that oxidized particle were fabricated.The surface of powders were oxidized.I used crystal of GaNSEM image21AblationVacuum stateAblation conditionsNd:YAG power :1.5mJ

Element analysis22Ablation

A broken piece by ablation

Ga mapping imageSEM imageEDS dataNitrogen was observed.Element analysis23Ablation

Fabricated particle by ablation

Ga mapping imageSEM imageEDS dataNitrogen peak was expected. 24Particles have nitrogen defect.Superfluid Helium condition25AblationSuperfluid HeliumLow temperatureViscosity becomes zero.Resonant energy very sharpSmall destabilizing effectSuitable for optical manipulationThe particles can be cool rapidly.For ablationCrystal of GaN26AblationSuperfluid He stateAblation conditionsNd:YAG power 0.5mJ

Crystal of GaN27Ablation

Ga mapping imageSEM imageNitrogen peak was expected. EDS data28Particles have nitrogen defect.Results29AblationThe particles had nitrogen defect and contained oxygen.Tablet from powderVacuum conditionsuperfluid He conditionIn such conditionCrystalVacuum conditionsuperfluid He conditionOptical manipulation30Zinc Oxides31manipulationBand-gap energy of ZnO is 3.4eV.Wide-gap semiconductor

1mm1 cmPolygonal shape ZnO is very stable material, because Its oxidation products.Problem of size distribution32manipulationAdvantage of particleDensity of stateSize distributionDensity of state becomes cloudy.Density state become sharply.Pulse laser spectra33manipulation

Pulse durationPeak energySpectrum width1ps100fs3.38eV3.38eV2meV20meVfs pulse laserps pulse laserResonance radiusunder 100nm radiusspecific radiusY. Saito Master thesis (2009)Decrease of size distribution34manipulationY. Saito Master thesis (2009)

fs pulse laserps pulse laserThe Size distribution reduced in response to spectrum width.I try to measure size distribution from spectrum width of photoluminescence.Summary35Optical fabricationI cant fabricate GaN particlesOptical manipulationThe particles fabricated by ablation have nitrogen defect and contained oxygen.I try to measure size distribution from spectrum width of photoluminescence.Appendix36Photo induced force37Appendix

Gradient forceRadiation pressure

Optical letters vol.11, No. 5, 288 (1986)First experiment38Appendix

transparent latex spheressizematerial0.59, 1.31, 2.68mmCW argon laserl = 0.5145mmw0= 6.2mmPower 19mWThe author measured sphere moved at 265mm/secsampleslaserTEM00Laser cooling39

Quantum confinement40Appendixa > aba:ab:2a2abE2a2a2abab > aCuCl0.68nmnm


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