DAFS - Universidad de Zaragoza

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$Difracción de Rayos X, neutrones y electrones$

Applications : Nanostructures III-V : BQ GaN/AlN ~ 30o TEM [0001] AlN GaN QDs BV BV h= 4 nm D b = 30 nm BC BC { 11 03} 5 nm A.D. Andreev et E.P. O’Reilly, APL 79, (2001), 521 P Nitride : InN (1,9eV), GaN (3,5eV), AlN (6,2eV) + alloys : visible spectra + UV A and B : LEDs (B, V) , LDs at 0,4µm - QDs : dislocations free - 3D electronic onfinement : - higher PL intensity - PL intensity : T independant - Wurtzite (hexagonal cell) : [0001] : polar axis) : spontaneous + piezo-electric polarizations : electric field - PL red shift - carriers separation Important parameters : deformation, size, composition 34/50
Applications : Nanostructures III-V : BQ GaN/AlN GaN QDs (4ML) wetting layer (2ML) AlN buffer (40 ML) Saphir or SiC substrates AlN capping of a GaN/AlN QDs layer : strain, composition, mechanism ? AFM - Modified Stranski – Krastanow growth (MBE) - AlN, GaN mismatch : 2,4 % Ga + N GaN thickness > critical thickness GaN QDs AlN RHEED 35/50
Page 1 and 2: Universidad de Zaragoza Curso de Ma
Page 3 and 4: TÉCNICAS EXPERIMENTALES µ I diff
Page 5 and 6: EL DAFS El DAFS es la estructura fi
Page 7 and 8: Resonant atomic scattering factor f
Page 9 and 10: y 0 Structure factor: Multi-wavelen
Page 11 and 12: I F diff 0 F 0 Análisis de datos D
Page 13 and 14: Using the path formalism for descri
Page 15 and 16: Spatial selectivity : GaAs xP 1-x/G
Page 17 and 18: TEM InAs/InP QWrs AFM 200nm GaN/AlN
Page 19 and 20: Local structure study of InAs/InP Q
Page 21 and 22: As-O As K-edge EXAFS (BM8-ESRF) Int
Page 23 and 24: Grazing incidence diffraction BM2-D
Page 25 and 26: GI-DAFS (Grazing Incidence DAFS) k(
Page 27 and 28: Diffraction Intensity (a.u.) GIDAFS
Page 29 and 30: Abs II EXAFS and EDAFS best fit res
Page 31 and 32: GIDAFS oscillations analysis CP1276
Page 33: EXAFS (ε // & ε ⊥) Similar resu
Page 37 and 38: Applications : Nanostructures III-V
Page 39 and 40: BQ GaN/AlN 10ML : EXAFS vs DAFS k
Page 41 and 42: BQ GaN/AlN : EDAFS simulations h=2.
Page 43 and 44: Orden de carga y reflexiones prohib
Page 45 and 46: Estado electrónico de los sitios o
Page 47 and 48: Anisotropía del factor de dispersi
Page 49 and 50: Zona del umbral (DANES) Modelo refl
Page 51 and 52: Prepico Cálculos “ab initio” d
Page 53: Grazing Incidence Diffraction Anoma

DAFS - Universidad de Zaragoza

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