A5013011552- Semiconductor materials and devices
- ZnO doping and properties
- GaN-based semiconductor devices and materials
- Electron and X-Ray Spectroscopy Techniques
- Semiconductor Quantum Structures and Devices
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Chemical Physics Studies
- Semiconductor materials and interfaces
- Copper-based nanomaterials and applications
- Electronic and Structural Properties of Oxides
- Ga2O3 and related materials
- Machine Learning in Materials Science
- Ion-surface interactions and analysis
- Advanced Semiconductor Detectors and Materials
- Chalcogenide Semiconductor Thin Films
- Magnetic and transport properties of perovskites and related materials
- Metal and Thin Film Mechanics
- X-ray Diffraction in Crystallography
- Quantum Dots Synthesis And Properties
- Advanced X-ray Imaging Techniques
- Enzyme Structure and Function
- Nuclear Physics and Applications
- Catalytic Processes in Materials Science
- Photorefractive and Nonlinear Optics
- Rare-earth and actinide compounds
Synchrotron soleil
2015-2024
European Synchrotron Radiation Facility
2003-2010
Direction de la Recherche Fondamentale
2004
We investigate the local structure of ferromagnetic Zn(1-x)Co(x)O epilayers by coupling polarization-dependent x-ray absorption spectroscopy and ab initio calculations selected defect structures. give clear evidence presence oxygen vacancies, located close to Co atoms in a specific complex configuration. also establish upper concentration limit metallic parasitic nanophases their contribution magnetism. Our results lead conclusion that vacancies play an important role originating high...
The SIRIUS beamline of Synchrotron SOLEIL is dedicated to X-ray scattering and spectroscopy surfaces interfaces, covering the tender mid-hard range (1.1-13 keV). has hosted a wide experiments in field soft interfaces beyond, providing various grazing-incidence techniques such as diffraction wide-angle (GIXD/GIWAXS), small-angle (GISAXS) fluorescence total reflection (TXRF). also offers specific sample environments tailored for situ complementary on solid liquid surfaces. Recently, added...
We use x-ray absorption spectroscopy to investigate the local structure around Bi atoms in ${\text{GaAs}}_{1\ensuremath{-}x}{\text{Bi}}_{x}$ layers grown on GaAs as a function of concentration order detect short-range order. find that static disorder next-nearest-neighbor interatomic distances dramatically increases when is increased. At 1.2% concentration, are randomly distributed whereas at 1.9%, they tend form pairs. When rises 2.4%, our results suggest some small clusters. Such strong...
A complementary suite of in situ synchrotron X-ray techniques is used to investigate both structural and chemical evolution during ZnO growth by atomic layer deposition. Focusing on the first 10 cycles growth, we observe that structure formed coalescence stage largely determines overall microstructure film. Furthermore, comparing silicon with a native oxide Al2O3(001), find even lattice-mismatched substrates low deposition temperatures, crystalline texture films dependent strongly nature...
GaAsN alloys belong to a class of semiconductors with fascinating physical properties. Indeed, small amount nitrogen incorporation in GaAs leads counterintuitive and large band-gap reduction, an unexpected sudden increase the effective mass electrons. Even more surprisingly, both electronic structural changes can be reversed fully tunable manner by hydrogen incorporation. In this paper, we combine x-ray absorption spectroscopy at edge ab initio simulations investigate atomic geometry...
Deuterium (hydrogen) incorporation in dilute nitrides (e.g., GaAsN and GaPN) modifies dramatically the crystal's electronic structural properties represents a prominent example of defect engineering semiconductors. However, microscopic origin D-related effects is still an experimentally unresolved issue. In this paper, we used nuclear reaction analyses and/or channeling, high resolution x-ray diffraction, photoluminescence, absorption fine structure measurements to determine how...
We address the compositional evolution of structure ${\text{GaAs}}_{1\ensuremath{-}x}{\text{Bi}}_{x}$ thin films at different scale lengths by combining x-ray absorption spectroscopy, atomic force microscopy, and diffraction. find that Bi short range ordering, observed for $x<3\mathrm{%}$, drastically vanishes $x\ensuremath{\ge}5.4\mathrm{%}$. The recovery random anion distribution goes along with formation droplets sample surface while bulk maintains high crystalline quality. These...
The aim of this work is to investigate the possibility extracting correct structural parameters from fluorescence EXAFS data taken at high count rates with an energy-resolving detector. This situation often encountered on third-generation synchrotron radiation sources which provide a flux sample. Errors caused by pulse pile-up in extraction information have been quantified real experiment, and different approaches problem correction elaborated. are discussed comparison ability each kind...
Impressive changes in the transport and ferromagnetic properties of Co-doped ZnO thin films have been obtained by postgrowth hydrogen irradiation at temperatures 400 °C. Hydrogen incorporation increases saturation magnetization one order magnitude (up to ∼1.50 μB/Co) carrier density mobility about a factor two. In addition magnetic characterization, structural hydrogenated ZnO:Co investigated Hall effect, local probe conductivity measurements, micro-Raman, X-ray absorption spectroscopy....
We study the effect of hydrogen incorporation on lattice properties ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{As}}_{1\ensuremath{-}y}{\mathrm{N}}_{y}/\mathrm{GaAs}$ heterostructures. The band gap widening observed in photoluminescence spectra hydrogenated ${\mathrm{GaAs}}_{1\ensuremath{-}y}{\mathrm{N}}_{y}$ and ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{As}}_{1\ensuremath{-}y}{\mathrm{N}}_{y}$ is accompanied by a expansion along growth direction, as measured...
We addressed the issue of bismuth heteroantisite defects (BiGa) in GaAs1−xBix/GaAs epilayers by coupling x-ray absorption spectroscopy at edge with density functional theory calculations defect structure. Calculations predict a large relaxation Bi-As interatomic distances when Bi atoms substitute Ga, however we found no experimental evidence it. Quantitative analysis spectra allows us to establish maximum concentration limit for BiGa, which corresponds about 5% total atoms. BiGa do not...
The reduction of conductivity and the enhancement ferromagnetic order following Co-doping in ZnO films are interpreted within a (Co–V<sub>O</sub>)-mediated model magnetic coupling.
We have investigated the structure of nitrogen-hydrogen complexes in ${\text{GaAs}}_{1\ensuremath{-}y}{\text{N}}_{y}$ and ${\text{In}}_{x}{\text{Ga}}_{1\ensuremath{-}x}{\text{As}}_{1\ensuremath{-}y}{\text{N}}_{y}$ dilute nitride alloys by performing x-ray absorption near-edge spectroscopy (XANES). simulated spectra based on first-principles calculations most recent defective structures proposed literature for hydrogenated materials. The comparison between experimental data simulations allows...
We have used an experimental strategy that, combining nuclear reaction analysis and Rutherford backscattering spectrometry both in random channeling geometry, allowed accurate quantification of the total amount N InxGa1−xNyAs1−y/GaAs GaNyAs1−y/GaAs epitaxial systems (0.038&lt;x&lt;0.044, 0.015&lt;y&lt;0.045), a precise localization nitrogen atoms into lattice. All were found on substitutional positions. This information was then exploited to correlate relaxed lattice...
We investigated the local structure around N and Sb atoms in $\mathrm{Ga}\mathrm{As}\mathrm{Sb}\mathrm{N}∕\mathrm{Ga}\mathrm{As}$ epilayers as a function of growth conditions annealing time via soft hard x-ray absorption spectroscopies order to find out if short range ordering (SRO) group-V sublattice is present. SRO one potential origins huge blueshift band gap observed upon these materials. By combining $K$- $L$- $K$-edge fine spectroscopy analysis, we demonstrate that neither strong...
The growth of zinc oxide thin films by atomic layer deposition is believed to proceed through an embryonic step in which three-dimensional nanoislands form and then coalesce trigger a layer-by-layer mode. This transient initial state characterized poorly ordered structure, may be inaccessible X-ray diffraction techniques. In this work, we apply absorption spectroscopy situ address the local structure Zn after each cycle, using custom-built reactor mounted at synchrotron beamline, shed light...
Short-range ordering in the form of an excess In-N bonds with respect to random case has been recently predicted for dilute nitride alloy ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{As}}_{1\ensuremath{-}y}{\mathrm{N}}_{y}.$ This induces a blue shift optical band gap and could represent fundamental materials limitation. In this report we provide quantitative determination effect annealing on short-range...
Growth per cycle. Visualizing the fabrication of a ZnO ultra-thin layer at very early stage ALD on InGaAs substrate, before 3D growth mode begins.
In this paper we investigate the incorporation of hydrogen in ${\text{Ga}}_{1\ensuremath{-}x}{\text{Mn}}_{x}\text{As}$ for samples with $x\ensuremath{\approx}0.005$ grown by metal-organic vapor-phase epitaxy and $0.03<x<0.05$ low-temperature molecular-beam epitaxy. The anisotropic electron-paramagnetic-resonance (EPR) signal observed paramagnetic after hydrogenation is characteristic ${\text{Mn}}^{2+}$ substitutional on Ga site. Contributions crystal fields to EPR indicative Mn-H complexes H...
Postgrowth hydrogen incorporation in In-rich In${}_{x}$Ga${}_{1\ensuremath{-}x}$N ($x>0.4$) alloys strongly modifies the optical and structural properties of material: A large blueshift emission absorption energies is accompanied by a remarkable broadening interatomic-distance distribution, as probed synchrotron radiation techniques. Both effects vanish at finite In-concentration value ($x$ \ensuremath{\sim} 0.5). Synergic x-ray measurements first-principle calculations unveil two different...
By means of micro-structural and optical characterization the Yb:Nb:RbTiOPO(4) crystal, we demonstrated that broad emission band Yb(3+) in these crystals is due to large splitting ytterbium ground state only, not a complex multisite occupation by ions crystals. We used this demonstrate wide laser tuning range generation femtosecond pulses. Passive mode-locked operation has been realized using semiconductor saturable absorber mirror, generating ultra short pulses 155 fs, which were very...
A new high-vacuum multipurpose diffractometer (called FORTE from the French acronyms of project) has recently been installed at tender/hard X-ray SIRIUS beamline Synchrotron SOLEIL, France. The geometry chosen allows one to work either in classical Eulerian four-circle for bulk diffraction (XRD) or z -axis surface XRD. nicely fits characteristics beamline, optimized 1.1–4.5 keV range, and perform unprecedented anomalous fine structure (DAFS) experiments tender region, also around...
Although it is well known that dilute species often significantly modify the properties of solids in which they are hosted, a basic question remains open: How critical their local determining macroscopic ones host material? Here we address this issue by taking N III-V-N alloys as paradigmatic case and propose an original approach based on synergic progress x-ray spectroscopies, density functional theory simulations, hydrogen exposure tool to bonding. In way able clarify how operate...