Hercules Part II 30H Renevier CEA Grenoble

Hubert Renevier

Description

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

Sujets

• Renevier
• Structure

Informations

• Publié par: larec
• Nombre de lectures: 35
• Poids de l'ouvrage: 2 Mo

Extrait

Anomalous Diffraction and Diffraction Anomalous Fine Structure Part II Application to the study of heterostructuresandsemiconductor nanostructures H. Renevier/CEA-Grenoble H. Renevier [e-mail] Hercules 30/03/06 Part II03/1

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

Diffraction AnomalousFine Structure spectroscopy: experiment To measurethediffuse scattering/diffraction intensity: -as functionofthex-raybeam energyacrossabsorption edges -atfixedscatteringvectors -overa 1000eV range witha high S/N ratio (atleast 10 3 ) Energy-scan diffraction : Ti foil H. Renevier/CEA-Grenoble Q sample gemoa LIII Pt 4.0 0.3 ( 001 ) 2.0 Pt L III -edge 114001160011800120001220012400 CoPtthinfilm Diffraction detector twotheta Hercules 30/03/06 Part II03/3

Diffraction Anomalous Fine Structure at BM2 FixQ energy-scandiffraction 9 Bragg peakmaximum-intensity measurements(withrocking- sampleholder+ feedback control), 9 Bragg peakintegration 9 Quick DAFS 9 Photodiode-based detector: lownoise and highdynamicrange 52.0 2.0 2.0 51.0 yarx sample ω axis GaK-edge 1.0 1036010365103701037510380 51.0 1.0 50.0 0 102001040010 E 6 n 00 ergy (e 10 V 8 ) 001100011200 )Ve(E (006) InAsPthinfilm 1keV, 4mn ! H. Renevier, S. Grenier, S. Arnaud, J.F. Bérar, B. Caillot, J.L. Hodeau, A. Letoublon M.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-wavelength anomalousdiffraction (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 analysis Hercules 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 • ( D 1 A 9 F 92 S )   . s  I p . e J c . t P r i o c s k c e o r p in y g :  e H t .     a S l. r ,  a J g . ie A r m e .  t  C a h l. e ,  m P . h   y S s o . c   . R  1 e 1 v. 5   , L  6 et 3 t 0 .  2 2 ,  1 ( ,  1 3 9 0 9 6 3) 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 G a r p a p z l i i n c g a   t I io n n ci s dence DAFS  H. Renevier/CEA-GrenobleraP 60/30/03 selucreHII t/703

4.0 3.0 2.0 DAFS Spectroscopy •Probes theLocal environment, electronicstructure(empty states) ofresonantatomsselectedwithdiffraction (scattering) •Chemical, shell(resonance) andsite(interference) selective eborp LIII Pt 100 )( Pt L III -edge 114001160011800120001220012400 CoPtthinfilm H. Renevier/CEA-Grenoble ) 21.0 0.1 ( 420 0.08 As K-edge 1180011900120001210012200123001240012500 Energie (eV) NanostructuresInAs 4 ⎛ 1511 ⎞ ⎜⎟ 3 ⎝224⎠ 2 V K-edge 1 5 0 45054605470548054905500 Energie (eV) NaV 2 O 5 Hercules 30/03/06 Part II8/30

Spatial selectivity : GaAs x P 1-x /GaAsepilayer(x ≈ 0.20) DAFS : to investigate the strain accomodation in the strained epilayer XR )E(I θ 1 θ 2 GaAsP Tensilein plane strain θ 1 ≠θ 2 GaAs ]001[ •Chemical selectivity ε = (a GaAsP -a GaAs )/a GaAs •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 experiment M.G. Proietti, H. Renevier et al., Phys. Rev. B 59, (1999), 5479. H. Renevier/CEA-GrenobleHercules 30/03/06 Part II9/30

χ H. Renevier/CEA-Grenoble 200ms/pt 46810121416 1- k k (  ( Å Å - ) 1 ) 0-50. 10 ms/pt 0 10500 11000 11500 12000 E En n erg e ie r  (e g V) y 0.05 EDAFS oscillations GaKedge )k( 0 t=4000Å %7 - ]01 t=600Å 0123456 R (Å -1 ) )Å(R Hercules 30/03/06 Part II10/30 2.0 0 2.0- 24681012 k (Å -1 ) k(Å -1 ) 2.0 0 2.0- 2.0 0 2.0- Spatial selectivity : GaAs x P 1-x /GaAsepilayer G Q a ui A c s k P   / D G A a F A S s , t a h s in sis f t il e m d , w ( i 0 t 0 h 6) f   e w e e d a b k ac r k ef : l   e 2 c 0 ti 0 o 0 n e ,  V F ,  W 7  H m M in = u 0 t . e 0 s 2  ! ° ! 0.2 DAFS As Kedge (006) reflection, Ga K-edge GaKedge 0.2 0 FT 0.1 -0.2 1[   .0 = ε ]011[   %7.0 = ε ]011[   %6.0 = ε ]011[   %4.0 = ε

θ θ 2 1 Site selectivity: structure ofsuperlatticeinterfaces Q LS buffer Crystallographic co-refinement of : -three anomalous diffraction spectra Ir/Fe (Q along [001]), measured at 6.9, 7.3 Ir(100)-buffer (- 200 Å ) SL and 11.1 keV (Fe K-edge and Ir K- MgO substrate edge) DAFS atFeK-edge -the “smooth”DAFS of 5 reflections (0 0 44) (0 0 42) 1 Ir + 1.64Å (0 0 40) Fe11 1.60Å 42% %71  (0 0 38) 1.53Å Å54.1 (0 0 36) Energy H. Renevier/CEA-Grenoble 1eF 1.4 m 4Å Hercules 30/03/06 Part II11/30