X-Ray Photoelectron Diffraction Measurements of Hexagonal GaN(0004) Thin Films

1997 ◽  
Vol 468 ◽  
Author(s):  
R. Denecke ◽  
J. Morais ◽  
C. Wetzel ◽  
J. Liesegang ◽  
E. E. Haller ◽  
...  
Keyword(s):  
Thin Films ◽  
Theoretical Calculation ◽  
Intensity Ratio ◽  
Single Scattering ◽  
Forward Scattering ◽  
Surface Contamination ◽  
Cluster Calculation ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Sapphire Substrates

ABSTRACTWe report on the first scanned-angle x-ray photoelectron diffraction measurements on GaN(0001) in the wurtzite structure, as grown on sapphire substrates using MOCVD. These as-grown samples reveal forward scattering peaks in agreement with a theoretical calculation using a single scattering cluster calculation. The surface contamination by O and C does not exhibit any clear structure. From the combination of experiment and theoretical calculation and from a simple intensity ratio argument the surface termination for these samples could be determined to be N. The data also indicate that C is on average closer to the GaN surface than O.

The Use of the Conventional Isolated Atom Model for the Theoretical Calculation of the Dependence of Lβ/Lα: Intensity Ratio on the Sample Exit Angle for Unoxidized and Oxidized Transition Metal Alloy Thin Films

1991 ◽  
Vol 35 (B) ◽  
pp. 845-850
Author(s):  
Francis Fujiwara ◽  
George Andermann
Keyword(s):  
Thin Films ◽  
Transition Metal ◽  
Fluorescence Spectroscopy ◽  
Intensity Ratio ◽  
Exit Angle ◽  
Absorption Coefficients ◽  
Theoretical Formulation ◽  
Transition Metal Alloy ◽  
X Ray ◽  
Transition Metal Surfaces

Variable sample exit angle x-ray fluorescence spectroscopy (VEA-XRF) employing the Lβ/Lα intensity ratio for transition metals and their oxides has been shown to be useful for non-destructively studying transition metal surfaces and oxidation, as well as, superconductors. Thus the theoretical formulation of the Lβ/Lα intensity ratio dependence on the sample exit angle, θe, is of some interest and we develop it here. We also present methods of obtaining parameters needed in the formulation, such as Lβ absorption coefficients, which are not available in the literature, for wavelengths greater than about 12Å.

X-ray photoelectron diffraction study of dopant effects in La0.7X0.3MnO3 (X = La, Sr, Ca, Ce) thin films

2013 ◽  
Vol 113 (6) ◽  
pp. 063511 ◽  
Author(s):  
C. Raisch ◽  
C. Langheinrich ◽  
R. Werner ◽  
R. Kleiner ◽  
D. Koelle ◽  
...  
Keyword(s):  
Thin Films ◽  
Diffraction Study ◽  
X Ray ◽  
Photoelectron Diffraction

STRUCTURAL DETERMINATION OF THE Si/Cu(110) INTERFACE BY PHOTOELECTRON DIFFRACTION

1997 ◽  
Vol 04 (06) ◽  
pp. 1331-1335 ◽  
Author(s):  
C. ROJAS ◽  
J. A. MARTÍn-GAGO ◽  
E. ROMÁN ◽  
G. PAOLUCCI ◽  
B. BRENA ◽  
...  
Keyword(s):  
Room Temperature ◽  
Structural Parameters ◽  
Single Scattering ◽  
Structural Determination ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
First Order ◽  
Proposed Model ◽  
Laboratory Source

Deposition of 0.5 Si monolayer (ML) on a Cu (110) surface at room temperature (RT) leads to the formation of a c(2×2) LEED pattern. In order to find out the surface atomic structure of this ordered phase, X-ray photoelectron diffraction (XPD) azimuthal scans at different photon energies and full hemispherical XPD patterns of the Si 2 p core level have been measured using both synchrotron radiation and a laboratory source. We present an atomic model for the surface structure based on the examination of forward scattering and first order interference XPD features. Refinement of the structural parameters was achieved by performing single scattering cluster (SSC) calculations. In the proposed model Si atoms replace Cu atoms at the surface along the [Formula: see text] atomic rows.

THE SURFACE STRUCTURE OF A LOW Pd Cu/Pd-(110) CRYSTAL ALLOY

1994 ◽  
Vol 01 (04) ◽  
pp. 569-571 ◽  
Author(s):  
M. BOWKER ◽  
M. NEWTON ◽  
S.M. FRANCIS ◽  
M. GLEESON ◽  
C. BARNES
Keyword(s):  
Surface Structure ◽  
Surface Region ◽  
Single Scattering ◽  
Alloy Surface ◽  
High Concentration ◽  
Near Surface ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Layer 2

X-ray photoelectron diffraction studies of this alloy surface have been carried out and indicate that there is a significant expansion of the lattice in the near-surface region due to the high concentration of Pd in layer 2. Preliminary single scattering calculations lend support to this proposal for the surface structure, and place this expansion in the subsurface mainly between layers 2 and 3.

Characterization of Sol-Gel Derived (Pb,Ba)(Zr,Ti,Nb)O3 Thin Films for Optical Waveguide Development

1994 ◽  
Vol 343 ◽  
Author(s):  
P. F. Baude ◽  
J. S. Wright ◽  
C. Ye ◽  
L. F. Francis ◽  
D. L. Polla
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sapphire Substrates ◽  
Solution Preparation ◽  
Transmission Measurements ◽  
Gel Technique

ABSTRACT(PbBa)(ZrTiNb)03 thin films and powders have been prepared using the sol-gel technique. Solutions were synthesized in 2-methoxyethanol based upon our previous PZT solution preparation. Three different approaches were used for incorporating barium into PZT alkoxide solutions. Thermal analysis and x-ray diffraction results indicated that barium methoxypropoxide gave the best results. PBZTN (71% Pb and 71% Zr) was deposited onto sapphire substrates as well as oxidized silicon substrates. Optical transmission measurements showed greater than 80% transmission for wavelengths longer than 400 nm. Films with thickness of 3000 Å on sapphire exhibited a refractive index of 2.19 at λ=633 nm.

Soft X-Ray Valance State Effects in Conductors

1969 ◽  
Vol 13 ◽  
pp. 136-157 ◽  
Author(s):  
J. E. Holliday
Keyword(s):  
Thin Films ◽  
Transition Metal ◽  
Intensity Ratio ◽  
Low Energy ◽  
Ionic Character ◽  
Electrode Geometry ◽  
Band Shape ◽  
X Ray ◽  
Electronegativity Difference ◽  
Band Spectra

Investigation of the NiLIII band at various excitation voltages and the use of Ni and Ti thin films in the path of the NiLII,III and TiLII,III radiation, has shown that with proper electrode geometry and using target voltages of about 4 kv the effect of self absorption on emission edge shift and band shape is negligible for these elements. However, the LII/LIII intensity ratio of titanium is strongly effected by self absorption, but it is not effected for nickel and iron by self absorption.A survey of several investigators’ soft x-ray band spectra from alloys and conducting compounds showed that the observed band changes were related to the electronegativity difference of the combining elements or the ionic character of the band. Peaks appearing on the low energy side of transition metal bands when combined with 2nd period elements appear to be a cross transition between the 2s or 2p band of the non-metal and inner level of the metal.

GROWTH OF ULTRATHIN Mn FILMS ON Ag(100)

1997 ◽  
Vol 04 (06) ◽  
pp. 1251-1256 ◽  
Author(s):  
P. SCHIEFFER ◽  
M. C. HANF ◽  
C. KREMBEL ◽  
M. H. TUILIER ◽  
G. GEWINNER ◽  
...  
Keyword(s):  
Polar Angle ◽  
Atomic Plane ◽  
Atomic Layer ◽  
Single Scattering ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Maximum Value ◽  
Fcc Lattice ◽  
Place Exchange ◽  
X Ray Absorption

Mn films with a thickness of one monolayer have been deposited, in ultrahigh vacuum, on a Ag (100) single crystal at room temperature, and analyzed by X-ray photoelectron diffraction (XPD) and surface extended X-ray absorption fine structure (SEXAFS). The strong enhancement of the X-ray photoelectron Mn2p3/2 signal along the Ag[1100] direction indicates that a substantial fraction of the Mn atoms is located within the second topmost atomic layer. The SEXAFS data demonstrate that the Mn – Ag and Mn – Mn first neighbor distances are the same as the Ag – Ag distances in the Ag lattice; as a result, the atoms occupy Ag sites on the fcc lattice. Comparison of the experimental data with FEFF calculations indicates that a superficial Mn – Ag alloy is formed. If the film is mildly (330 K) annealed, the contrast in the XPD Mn 2p 3/2 modulations versus polar angle increases and reaches a maximum value of 60%. As confirmed by single scattering simulations, these results mean that atomic place exchange occurs between Mn and Ag atoms, and eventually the second atomic plane of the sample is constituted mainly by Mn atoms, whereas the first atomic layer is a pure Ag plane, i.e. a buried atomic Mn monolayer is formed.

Sign in / Sign up

Export Citation Format

Share Document