X-ray Excited Optical Luminescence Studies of InGaN and Rare-Earth Doped GaN Epilayers

2004 ◽  
Vol 831 ◽  
Author(s):  
V. Katchkanov ◽  
J.F.W. Mosselmans ◽  
K.P. O'Donnell ◽  
N.R.J. Poolton ◽  
S. Hernandez
Keyword(s):  
Rare Earth ◽  
Yellow Emission ◽  
Core Excitation ◽  
Yellow Band ◽  
X Ray ◽  
Optical Luminescence ◽  
Optically Detected ◽  
First Time ◽  
X Ray Absorption ◽  
Rare Earth Doped

ABSTRACTA successful attempt to use X-ray Excited Optical Luminescence (XEOL) for the detection of Extended X-ray Absorption Fine Structure (EXAFS) in III-nitrides is reported. The samples studied were InGaN and rare-earth (RE) doped GaN epilayers. For the first time Ga K-edge EXAFS oscillations were measured by monitoring the well-known “yellow” emission of GaN at 560 nm. The analysis of Optically Detected (OD) EXAFS data confirmed the expected local structure for Ga in GaN. The intensity oscillation of the “yellow” band when X-ray energy was scanned across the Ga K-edge indicates that core excitation of Ga atom has a high probability of transfer to defects responsible for “yellow” emission.

X-ray absorption study of rare-earth doped molten BaCuO system in various oxygen partial pressures

1997 ◽  
Vol 282-287 ◽  
pp. 447-448 ◽  
Author(s):  
Makoto Kambara ◽  
Hari S. Chauhan ◽  
Akihiko Endo ◽  
Yuh Shiohara ◽  
Takateru Umeda
Keyword(s):  
Rare Earth ◽  
Absorption Study ◽  
X Ray ◽  
Partial Pressures ◽  
X Ray Absorption ◽  
Rare Earth Doped

Detecting sp2-bonded carbon in diamond using optically detected X-ray absorption spectroscopy

2011 ◽  
Vol 1 (SRMS-7) ◽  
Author(s):  
G. O. Jones ◽  
O. R. Roberts ◽  
G. T. Williams ◽  
D. P. Langstaff ◽  
N. R. J. Poolton ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Transmitted Light ◽  
X Rays ◽  
Lateral Variation ◽  
X Ray ◽  
Local Bonding ◽  
Optical Luminescence ◽  
Optically Detected ◽  
X Ray Absorption ◽  
Absorption Contrast

Optically detected X-ray absorption spectroscopy (ODXAS) and X-ray excited optical luminescence (XEOL) have been applied in parallel to the study of local bonding in luminescent diamonds. Imaging ODXAS and XEOL reveal correlations between lateral variation in colour (transmitted light and luminescence) and local carbon bonding in selected samples showing strong optical absorption contrast. Dark regions of the crystals viewed in transmitted light correlate with a lower total luminescence yield when excited with soft X-rays of photon energy ~280 eV. ODXAS reveals a higher proportion of sp2-bonded carbon species in darker (less luminescent) regions associated with graphitic micro-inclusions.

X-ray absorption fine structure of rare earth doped (La,Sr)2CuO4

1998 ◽  
Vol 299 (3-4) ◽  
pp. 191-196 ◽  
Author(s):  
T Niemöller ◽  
B Büchner ◽  
M Cramm ◽  
C Huhnt ◽  
L Tröger ◽  
...  
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
Rare Earth Doped

X-ray excited optical luminescence changes induced by excess/deficiency lithium ions in rare earth doped LiAl5O8

2018 ◽  
Vol 199 ◽  
pp. 298-301 ◽  
Author(s):  
Ariosvaldo J.S. Silva ◽  
Patresio A.M. Nascimento ◽  
Adriano B. Andrade ◽  
David V. Sampaio ◽  
Benjamin J.A. Moulton ◽  
...  
Keyword(s):  
Rare Earth ◽  
Lithium Ions ◽  
X Ray ◽  
Optical Luminescence ◽  
Rare Earth Doped

scholarly journals High Pressure X-ray Diffraction as a Tool for Designing Doped Ceria Thin Films Electrolytes

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 724
Author(s):  
Sara Massardo ◽  
Alessandro Cingolani ◽  
Cristina Artini
Keyword(s):  
Thin Films ◽  
High Pressure ◽  
Rare Earth ◽  
Ionic Conductivity ◽  
Bulk Material ◽  
Threshold Temperature ◽  
Doped Ceria ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rare Earth Doped

Rare earth-doped ceria thin films are currently thoroughly studied to be used in miniaturized solid oxide cells, memristive devices and gas sensors. The employment in such different application fields derives from the most remarkable property of this material, namely ionic conductivity, occurring through the mobility of oxygen ions above a certain threshold temperature. This feature is in turn limited by the association of defects, which hinders the movement of ions through the lattice. In addition to these issues, ionic conductivity in thin films is dominated by the presence of the film/substrate interface, where a strain can arise as a consequence of lattice mismatch. A tensile strain, in particular, when not released through the occurrence of dislocations, enhances ionic conduction through the reduction of activation energy. Within this complex framework, high pressure X-ray diffraction investigations performed on the bulk material are of great help in estimating the bulk modulus of the material, and hence its compressibility, namely its tolerance toward the application of a compressive/tensile stress. In this review, an overview is given about the correlation between structure and transport properties in rare earth-doped ceria films, and the role of high pressure X-ray diffraction studies in the selection of the most proper compositions for the design of thin films.

scholarly journals Revealing noncollinear magnetic ordering at the atomic scale via XMCD

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fridtjof Kielgast ◽  
Ivan Baev ◽  
Torben Beeck ◽  
Federico Pressacco ◽  
Michael Martins
Keyword(s):  
Ground State ◽  
Magnetic Circular Dichroism ◽  
Magnetic Moments ◽  
Magnetic Ordering ◽  
Atomic Scale ◽  
Angle Of Incidence ◽  
X Ray ◽  
First Time ◽  
X Ray Absorption ◽  
Magnetic Sublattices

AbstractMass-selected V and Fe monomers, as well as the heterodimer $${\text{Fe}}_1{\text{V}}_1$$ Fe 1 V 1 , were deposited on a Cu(001) surface. Their electronic and magnetic properties were investigated via X-ray absorption (XAS) and X-ray magnetic circular dichroism (XMCD) spectroscopy. Anisotropies in the magnetic moments of the deposited species could be examined by means of angle resolving XMCD, i.e. changing the X-ray angle of incidence. A weak adatom-substrate-coupling was found for both elements and, using group theoretical arguments, the ground state symmetries of the adatoms were determined. For the dimer, a switching from antiparallel to parallel orientation of the respective magnetic moments was observed. We show that this is due to the existence of a noncollinear spin-flop phase in the deposited dimers, which could be observed for the first time in such a small system. Making use of the two magnetic sublattices model, we were able to find the relative orientations for the dimer magnetic moments for different incidence angles.

scholarly journals Determination of the relative concentrations of rare earth ions by x-ray absorption spectroscopy: Application to terbium mixed oxides

1986 ◽  
Vol 47 (4) ◽  
pp. 413-416 ◽  
Author(s):  
G. van der Laan ◽  
J.C. fuggle ◽  
M.P. van Dijk ◽  
A.J. Burggraaf ◽  
J.-M. Esteva ◽  
...  
Keyword(s):  
Rare Earth ◽  
Absorption Spectroscopy ◽  
Mixed Oxides ◽  
Rare Earth Ions ◽  
X Ray ◽  
X Ray Absorption

scholarly journals Local and electronic structure around Ga in CdTe: evidence of DX- and A-centers

2012 ◽  
Vol 20 (1) ◽  
pp. 166-171
Author(s):  
Vasil Koteski ◽  
Jelena Belošević-Čavor ◽  
Petro Fochuk ◽  
Heinz-Eberhard Mahnke
Keyword(s):  
Density Functional ◽  
Plane Waves ◽  
Lattice Relaxation ◽  
Defect Structures ◽  
Functional Theory ◽  
Edge Structure ◽  
X Ray ◽  
First Time ◽  
X Ray Absorption ◽  
Good Agreement

The lattice relaxation around Ga in CdTe is investigated by means of extended X-ray absorption spectroscopy (EXAFS) and density functional theory (DFT) calculations using the linear augmented plane waves plus local orbitals (LAPW+lo) method. In addition to the substitutional position, the calculations are performed for DX- and A-centers of Ga in CdTe. The results of the calculations are in good agreement with the experimental data, as obtained from EXAFS and X-ray absorption near-edge structure (XANES). They allow the experimental identification of several defect structures in CdTe. In particular, direct experimental evidence for the existence of DX-centers in CdTe is provided, and for the first time the local bond lengths of this defect are measured directly.

Extended X-ray Absorption Fine Structure Studies of GaN Epilayers Doped in situ with Er and Eu During Molecular Beam Epitaxy

2003 ◽  
Vol 798 ◽  
Author(s):  
V. Katchkanov ◽  
J. F. W. Mosselmans ◽  
S. Dalmasso ◽  
K. P. O'Donnell ◽  
R. W. Martin ◽  
...  
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Molecular Beam Epitaxy ◽  
Local Structure ◽  
Molecular Beam ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
The Eu

ABSTRACTThe local structure around Er and Eu atoms introduced into GaN epilayers was studied by means of Extended X-ray Absorption Fine Structure above the appropriate rare-earth X-ray absorption edge. The samples were doped in situ during growth by Molecular Beam Epitaxy. The formation of ErN clusters was found in samples with high average Er concentrations of 32±6% and 12.4±0.8%, estimated by Wavelength Dispersive X-ray analysis. When the average Er concentration is decreased to 6.0±0.2%, 1.6±0.2% and 0.17±0.02%, Er is found in localised clusters of ErGaN phase with high local Er content. Similar behaviour is observed for Eu-doped samples. For an average Eu concentration of 30.5±0.5% clusters of pure EuN occur. Decreasing the Eu concentration to 10.4±0.5% leads to EuGaN clusters with high local Eu content. However, for a sample with an Eu concentration of 14.2±0.5% clustering of Eu was not observed.

Sign in / Sign up

Export Citation Format

Share Document