X-RAY Photoemission Spectroscopic Study of Light-Induced Structural Changes in Amorphous Silicon

2000 ◽  
Vol 609 ◽  
Author(s):  
Shuran Sheng ◽  
Edward Sacher ◽  
Arthur Yelon
Keyword(s):  
Amorphous Silicon ◽  
Structural Changes ◽  
Crystalline Silicon ◽  
Light Exposure ◽  
High Energy ◽  
Binding Energies ◽  
Irradiation Effect ◽  
Incident Intensity ◽  
Illumination Time ◽  
X Ray

ABSTRACTLight- and annealing-induced structural changes in undoped hydrogenated amorphous silicon (a-Si:H), pure amorphous silicon (a-Si) and crystalline silicon (c-Si) have been investigated in detail by X-ray photoemission spectroscopy (XPS). Both the Si2s and Si2p peaks in a-Si:H films were found to shift simultaneously to lower binding energies by the same amount with illumination time, and nearly reach saturation at about 0.06 eV after one hour of light-soaking at the intensity used. In contrast to the metastable changes in electronic properties [Staebler-Wronski effect (SWE)], the light-induced shifts in both peaks are unstable even at room temperature and can be reversed by annealing with a lower activation energy than that for the SWE. The absence of metastable XPS changes in pure a-Si and c-Si suggests that hydrogen is actively involved in the light-induced structural changes. Furthermore, visible light exposure produces XPS changes in a-Si:H less effectively than X-ray irradiation, despite its much higher incident intensity, indicating a high-energy photon irradiation effect. Our present results suggest that essentially the whole Si network structure is affected by light-soaking or X-ray irradiation, and becomes more stable after repeated irradiation-annealing training. These structural changes may be an independent metastable phenomenon or a precursor process of the SWE.

Structural changes in titanium dioxide nanocrystals during plastic deformation

2005 ◽  
Vol 38 (5) ◽  
pp. 749-756 ◽  
Author(s):  
Ulrich Gesenhues
Keyword(s):  
Structural Changes ◽  
Crystal Size ◽  
Lower Layer ◽  
High Energy ◽  
Primary Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hall Method ◽  
Means Of Transmission

The polygonization of 200 nm rutile crystals during dry ball-milling at 10gwas monitored in detail by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). The TEM results showed how to modify the Williamson–Hall method for a successful evaluation of crystal size and microstrain from XRD profiles. Macrostrain development was determined from the minute shift of the most intense reflection. In addition, changes in pycnometrical density were monitored. Accordingly, the primary crystal is disintegrated during milling into a mosaic of 12–35 nm pieces where the grain boundaries induce up to 1.2% microstrain in a lower layer of 6 nm thickness. Macrostrain in the interior of the crystals rises to 0.03%. The pycnometrical density, reflecting the packing density of atoms in the grain boundary, decreases steadily by 1.1%. The results bear relevance to our understanding of plastic flow and the mechanism of phase transitions of metal oxides during high-energy milling.

scholarly journals Structural Evolution in Wet Mechanically Alloyed Co-Fe-(Ta,W)-B Alloys

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 800
Author(s):  
Vladimír Girman ◽  
Maksym Lisnichuk ◽  
Daria Yudina ◽  
Miloš Matvija ◽  
Pavol Sovák ◽  
...  
Keyword(s):  
Structural Changes ◽  
Magnetic Measurements ◽  
Structural Evolution ◽  
High Energy ◽  
Control Agent ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Transmission Electron ◽  
X Ray Absorption

In the present study, the effect of wet mechanical alloying (MA) on the glass-forming ability (GFA) of Co43Fe20X5.5B31.5 (X = Ta, W) alloys was studied. The structural evolution during MA was investigated using high-energy X-ray diffraction, X-ray absorption spectroscopy, high-resolution transmission electron microscopy and magnetic measurements. Pair distribution function and extended X-ray absorption fine structure spectroscopy were used to characterize local atomic structure at various stages of MA. Besides structural changes, the magnetic properties of both compositions were investigated employing a vibrating sample magnetometer and thermomagnetic measurements. It was shown that using hexane as a process control agent during wet MA resulted in the formation of fully amorphous Co-Fe-Ta-B powder material at a shorter milling time (100 h) as compared to dry MA. It has also been shown that substituting Ta with W effectively suppresses GFA. After 100 h of MA of Co-Fe-W-B mixture, a nanocomposite material consisting of amorphous and nanocrystalline bcc-W phase was synthesized.

scholarly journals Beating absorption in solid-state high harmonics

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Hanzhe Liu ◽  
Giulio Vampa ◽  
Jingyuan Linda Zhang ◽  
Yu Shi ◽  
Siddharth Buddhiraju ◽  
...  
Keyword(s):  
Vacuum Ultraviolet ◽  
Crystalline Silicon ◽  
High Harmonic ◽  
Ultra Violet ◽  
Fold Increase ◽  
High Energy ◽  
High Order ◽  
Limiting Factor ◽  
X Ray ◽  
On Chip

Abstract Since the new millennium coherent extreme ultra-violet and soft x-ray radiation has revolutionized the understanding of dynamical physical, chemical and biological systems at the electron’s natural timescale. Unfortunately, coherent laser-based upconversion of infrared photons to vacuum-ultraviolet and soft x-ray high-order harmonics in gaseous, liquid and solid targets is notoriously inefficient. In dense nonlinear media, the limiting factor is strong re-absorption of the generated high-energy photons. Here we overcome this limitation by generating high-order harmonics from a periodic array of thin one-dimensional crystalline silicon ridge waveguides. Adding vacuum gaps between the ridges avoids the high absorption loss of the bulk and results in a ~ 100-fold increase of the extraction depth. As the grating period is varied, each high harmonic shows a different and marked modulation, indicating their waveguiding in the vacuum slots with reduced absorption. Looking ahead, our results enable bright on-chip coherent short-wavelength sources and may extend the usable spectral range of traditional nonlinear crystals to their absorption windows. Potential applications include on-chip chemically-sensitive spectro-nanoscopy.

Structural changes in nanocrystalline mackinawite (FeS) at high pressure

2008 ◽  
Vol 42 (1) ◽  
pp. 15-21 ◽  
Author(s):  
L. Ehm ◽  
F. M. Michel ◽  
S. M. Antao ◽  
C. D. Martin ◽  
P. L. Lee ◽  
...  
Keyword(s):  
High Pressure ◽  
Pair Distribution Function ◽  
Structural Changes ◽  
Function Analysis ◽  
Structural Phase ◽  
High Energy ◽  
Particle Sizes ◽  
Grain Size Effect ◽  
X Ray ◽  
First Order

The high-pressure behavior of nanocrystalline mackinawite (FeS) with particle sizes of 6, 7 and 8 nm has been investigated by high-energy X-ray total scattering and pair distribution function analysis. An irreversible first-order structural phase transition from tetragonal mackinawite to orthorhombic FeS-II was observed at about 3 GPa. The transition is induced by the closure of the van der Waals gap in the layered mackinawite structure. A grain size effect on the transition pressure and the compressibility was observed.

Ion Implantation Defect Characterization by High-Resolution X-Ray Diffraction

1992 ◽  
Vol 262 ◽  
Author(s):  
Jos G.E. Klappe ◽  
István Bársony ◽  
Tom W. Ryan
Keyword(s):  
High Resolution ◽  
Ion Implantation ◽  
Lattice Strain ◽  
Crystalline Silicon ◽  
High Energy ◽  
Silicon Sample ◽  
Dislocation Loops ◽  
X Ray Diffraction ◽  
X Ray ◽  
Residual Defect

ABSTRACTHigh-energy ion-implantation is one of the roost critical processing steps regarding the formation of defects in mono-crystalline silicon. High- as well as low-doses implanted at various energies can result in relatively high residual defect concentrations after post-implantation annealing.Before annealing, the crystal lattice strain is mainly caused by the point defects. After annealing, the accommodation of substitutional impurities is the main origin of the residual lattice strain. High-Resolution X-ray Diffraction (HRXD) has been frequently used for the characterization of these structures. Dislocation loops formed during the high temperature step, however, cause enhanced diffuse X-ray scattering, which can dominate the measured X-ray intensity in conventional HRXD.Triple axis diffractometry is used in this study to analyze the size, type and location of defects in a boron implanted and rapid thermally annealed silicon sample.

Structural studies on amorphous silicon boron nitride Si3B3N7: neutron contrast technique on nitrogen and high energy X‐ray diffraction

1999 ◽  
Vol 9 (11) ◽  
pp. 2865-2869 ◽  
Author(s):  
Ralf M. Hagenmayer ◽  
Utz Müller ◽  
Chris J. Benmore ◽  
Jörg Neuefeind ◽  
Martin Jansen
Keyword(s):  
Boron Nitride ◽  
Amorphous Silicon ◽  
High Energy ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Contrast Technique

scholarly journals Structure of Magnetically Ordered Si:Mn

2007 ◽  
Vol 131-133 ◽  
pp. 327-332 ◽  
Author(s):  
Jadwiga Bak-Misiuk ◽  
Elżbieta Dynowska ◽  
Przemyslaw Romanowski ◽  
A. Shalimov ◽  
Andrzej Misiuk ◽  
...  
Keyword(s):  
Structural Changes ◽  
Crystalline Silicon ◽  
Reciprocal Lattice ◽  
Grazing Incidence ◽  
Processing Parameters ◽  
Incidence Geometry ◽  
Geometry Processing ◽  
Reciprocal Lattice Point ◽  
X Ray ◽  
Disturbed Layer

The structure studies of single crystalline silicon implanted at 340 K or 610 K with Mn+ ions (Si:Mn) and subsequently processed under atmospheric and enhanced hydrostatic pressure at up to 1270 K are reported. The defect structure was determined by an analysis of X-ray diffuse scattering around the 004 reciprocal lattice point and by electron microscopy. High resolution X-ray diffraction techniques based on the conventional source of radiation were used for this purpose. The crystal structure of Si:Mn and the Si1-xMnx precipitates in the implantation – disturbed layer were studied by synchrotron radiation diffraction in the grazing incidence geometry. Processing of Si:Mn results in crystallization of amorphous Si within the buried implantation – disturbed layer and in formation of Mn4Si7 precipitates. Structural changes are dependent both on temperature of the Si substrate at implantation and on processing parameters.

Photo-Oxidation of Hydrogenated Amorphous Silicon-Carbon Alloys

1989 ◽  
Vol 158 ◽  
Author(s):  
P. John ◽  
I.M. Odeh ◽  
A. Qayyum ◽  
J.I.B. Wilson
Keyword(s):  
Amorphous Silicon ◽  
Photoelectron Spectroscopy ◽  
Crystalline Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Rf Discharge ◽  
Silicon Substrates ◽  
Capacitively Coupled ◽  
X Ray ◽  
Silicon Carbon ◽  
Hydrogenated Amorphous

ABSTRACTHydrogenated amorphous silicon-carbon alloys, a-Si:C:H, have been deposited as thin films (d=0.1-0.5 micron) on crystalline silicon substrates from a capacitively coupled rf discharge in silane-propane mixtures. Variations in the stoichiometry of the films were achieved by altering the ratio of SiH4 to C3H8 flow rates at a sbstrate temperature in the range 240-260°C and total pressure between 30-70 mtorr. The silicon to carbon ratios were established by X-ray photoelectron spectroscopy, XPS, and the hydrogen content and distribution by infra-red spectroscopy.

In Situ Monitoring of the Electrochemical Absorption of Deuterium into Palladium by X-Ray Diffraction using Synchrotron-Wiggler Radiation

1998 ◽  
Vol 524 ◽  
Author(s):  
D. D. Dominguez ◽  
P. L. Hagans ◽  
E. F. Skelton ◽  
S. B. Qadri ◽  
D. J. Nagel
Keyword(s):  
Structural Changes ◽  
National Laboratory ◽  
High Energy ◽  
Brookhaven National Laboratory ◽  
In Situ Monitoring ◽  
X Rays ◽  
X Ray ◽  
Β Phase ◽  
Metallic Sample

ABSTRACTWith low energy x-rays, such as those from a Cu x-ray tube, only the outer few microns of a metallic sample can be probed. This low penetrating power prohibits structural studies from being carried out on the interior of an electrode in an electrochemical cell because of absorption by the cell material, electrodes and the electrolyte. The work described in this paper circumvents this problem by utilizing high energy, high brightness x-rays produced on the superconducting wiggler beam line, X-17C, at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The penetrating power of the higher energy x-rays allowed Pd diffraction spectra to be obtained in-situ on a 1 mm diameter Pd wire cathode during electrolysis of heavy water. Moreover, the beam (28 × 28 μm in cross-section) allowed diffraction spectra to be acquired as a function of distance across the sample. Spectra were recorded in 50 μm steps from the edge of the Pd wire to its core. This was done at 2 minute intervals as a function of electrolysis time. The α-β phase transition induced in the Pd while deuterium was electrochemically absorbed was observed by monitoring the Pd-(422) diffraction peaks. Results allowed the diffusion rate and the diffusivity of deuterium atoms in the Pd wire to be determined. Other features of the structural changes associated with the absorption of deuterium into Pd are reported.

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