Hercules Part II 30H Renevier CEA Grenoble

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larec

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Niveau: Supérieur, Master, Bac+4
Hercules 30/03/06 Part II 1/30H. Renevier/CEA-Grenoble Anomalous Diffraction and Diffraction Anomalous Fine Structure Part II Application to the study of heterostructures and semiconductor nanostructures H. Renevier

diffraction anomalous

diffraction detector

intensity measurements

energy-scan diffraction

inasp thin

pt liii-edge

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Publié par

larec

Nombre de lectures

Poids de l'ouvrage

2 Mo

Renevier Structure

Anomalous Diffraction and Diffraction Anomalous Fine StructurePart IIApplication to the study of heterostructuresandsemiconductor nanostructuresH. Renevier/CEA-GrenobleH. RenevierHubert.Renevier@cea.frHercules 30/03/06 Part II03/1

Diffraction Anomalous Fine Structure at the french CRG (Collaborative Research Group) BM2-D2AM/ESRFExperimentH. Renevier/CEA-GrenobleeHII traP 60/30/03 selucr03/2

Diffraction AnomalousFine Structure spectroscopy: experimentTo measurethediffuse scattering/diffraction intensity:-as functionofthex-raybeamenergyacrossabsorption edges-atfixedscatteringvectors-overa 1000eV range witha highS/N ratio (atleast103)Energy-scandiffraction :Ti foilH. Renevier/CEA-GrenobleQsamplegemoaLIII Pt4.00.3(001)2.0Pt LIII-edge114001160011800120001220012400CoPtthinfilmDiffraction detectortwothetaHercules 30/03/06 Part II03/3

Diffraction Anomalous Fine Structure at BM2FixQ energy-scandiffraction9Bragg peakmaximum-intensitymeasurements(withrocking-sampleholder+ feedback control),9Bragg peakintegration9Quick DAFS9Photodiode-baseddetector: lownoise andhighdynamicrange52.02.02.051.0yarxsampleωaxisGaK-edge1.0103601036510370103751038051.01.050.00102001040010E6n00ergy (e10V8)001100011200)Ve(E(006) InAsPthinfilm1keV, 4mn !H. Renevier, S. Grenier, S. Arnaud, J.F. Bérar, B. Caillot, J.L. Hodeau, A. LetoublonM.G. Proietti, B. ravel, (2003), J. Synchrotron Rad. 10, 435-444.H. Renevier/CEA-GrenobleHercules 30/03/06 Part II4/30

Diffraction Anomalous Fine Structure at BM2-D2AM/ESRF•CRG beamline(Bendingmagnet)•dedicatedto multi-wavelengthanomalousdiffraction (MAD)•symmetricoptic: fixedexit•focussing•V : mirrors•H : sagittal, 2cd crystal•«Channel cut»monochromator•Stable (position/energy)H. Renevier/CEA-Grenoble•7-circle diffractometer•Diffraction : vertical/ horizontal planes•Polarisation analysisHercules 30/03/06 Part II5/30

•Earlyanomalousdiffraction observations : «Distribution spectrale dans les régions d’absorption propre de divers cristaux», Yvette Cauchois, comptes rendus, (1956), 242, 100–Bentcrystalanalyser–AnomalousDiffraction ofa mica cristal analyser (Al K-edge)•Diffraction AnomalousFine Structure:IztokArcon, et al., Journal de Physique, (1987), C9, 1105•(D1A9F92S) .s Ip.eJc. tPriocskceorpinyg: eHt. aSl.r, aJg.ieArme. t Cahl.e, mP.h ySso.c .R 1e1v.5 ,L 6et3t0. 22, 1(, 1390963)4, For reviewseealso:ResonantDiffraction. J.L. Hodeauet al., Chem. Rev., 101, (2001), 1843.H. Renevier/CEA-GrenobleHercules 30/03/06 Part II6/30

DAFS and Garpapzliincga tIionncisdence DAFS H. Renevier/CEA-GrenobleraP 60/30/03 selucreHII t/703

4.03.02.0DAFS Spectroscopy•Probes theLocal environment, electronicstructure(emptystates) ofresonantatomsselectedwithdiffraction (scattering)•Chemical, shell(resonance) andsite(interference) selectiveeborpLIII Pt100)(Pt LIII-edge114001160011800120001220012400CoPtthinfilmH. Renevier/CEA-Grenoble)21.00.1(4200.08As K-edge1180011900120001210012200123001240012500Energie (eV)NanostructuresInAs4⎛1511⎞⎜⎟3⎝224⎠2V K-edge15045054605470548054905500Energie (eV)NaV2O5Hercules 30/03/06 Part II8/30

Spatial selectivity : GaAsxP1-x/GaAsepilayer(x≈0.20)DAFS : to investigate the strain accomodation in the strained epilayerXR)E(Iθ1θ2GaAsPTensilein plane strainθ1≠θ2GaAs]001[•Chemical selectivityε= (aGaAsP-aGaAs)/aGaAs•Spatial selectivity, EXAFS do not have•The x-rays probe the entire thickness of the epilayer•The data analysis is easy (one site) as well as the experimentM.G. Proietti, H. Renevier et al., Phys. Rev. B 59, (1999), 5479.H. Renevier/CEA-GrenobleHercules 30/03/06 Part II9/30

χH. Renevier/CEA-Grenoble200ms/pt468101214161-kk( (ÅÅ-)1)0-50.10 ms/pt010500110001150012000EEnnergeier (egV)y0.05EDAFS oscillationsGaKedge)k(0t=4000Å%7-]01t=600Å0123456R (Å-1))Å(RHercules 30/03/06 Part II10/302.002.0-24681012k (Å-1)k(Å-1)2.002.0-2.002.0-Spatial selectivity : GaAsxP1-x/GaAsepilayerGQauiAcskP /DGAaFASs, tahsinsisftilemd, w(i0t0h6)f eweedabkacrkef:l e2c0ti0o0ne, VF, W7 HmMin=u0t.e0s2 !°!0.2DAFSAs Kedge(006) reflection, Ga K-edgeGaKedge0.20FT0.1-0.21[ .0 = ε]011[ %7.0 = ε]011[ %6.0 = ε]011[ %4.0 = ε

θθ21Site selectivity: structure ofsuperlatticeinterfacesQLSbufferCrystallographic co-refinement of :-three anomalous diffraction spectra Ir/Fe (Q along [001]), measured at 6.9, 7.3 Ir(100)-buffer (- 200 Å) SLand 11.1 keV (Fe K-edge and Ir K-MgO substrateedge)DAFS atFeK-edge-the “smooth”DAFS of 5 reflections(0 0 44)(0 0 42)1Ir+1.64Å(0 0 40)Fe111.60Å42%%71 (0 0 38)1.53ÅÅ54.1(0 0 36)EnergyH. Renevier/CEA-Grenoble1eF1.4m4ÅHercules 30/03/06 Part II11/30

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