scholarly journals Modified statistical dynamical diffraction theory: analysis of model SiGe heterostructures

2013 ◽  
Vol 46 (4) ◽  
pp. 912-918
Author(s):  
P. K. Shreeman ◽  
K. A. Dunn ◽  
S. W. Novak ◽  
R. J. Matyi
Keyword(s):  
Thin Film ◽  
Structural Information ◽  
Structural Characteristics ◽  
Diffraction Theory ◽  
Simulation Software ◽  
X Ray Diffraction ◽  
Theory Analysis ◽  
Dynamical Diffraction ◽  
X Ray ◽  
Kinematic Limit

A modified version of the statistical dynamical diffraction theory (mSDDT) permits full-pattern fitting of high-resolution X-ray diffraction scans from thin-film systems across the entire range from fully dynamic to fully kinematic scattering. The mSDDT analysis has been applied to a set of model SiGe/Si thin-film samples in order to define the capabilities of this approach. For defect-free materials that diffract at the dynamic limit, mSDDT analyses return structural information that is consistent with commercial dynamical diffraction simulation software. As defect levels increase and the diffraction characteristics shift towards the kinematic limit, the mSDDT provides new insights into the structural characteristics of these materials.

A new approach to wide-angle dynamical X-ray diffraction by deformed crystals

2006 ◽  
Vol 39 (5) ◽  
pp. 652-655 ◽  
Author(s):  
S. G. Podorov ◽  
N. N. Faleev ◽  
K. M. Pavlov ◽  
D. M. Paganin ◽  
S. A. Stepanov ◽  
...  
Keyword(s):  
High Resolution ◽  
Diffraction Data ◽  
Diffraction Theory ◽  
Simple Approach ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
New Approach ◽  
Dynamical Diffraction ◽  
X Ray ◽  
Distorted Waves

A new approach is proposed for X-ray dynamical diffraction theory in distorted crystals. The theory allows one to perform dynamical diffraction simulations between Bragg peaks for non-ideal crystals, using a simple approach of two distorted waves. It can be directly applied for reciprocal-space simulation. The formalism is used to analyse high-resolution X-ray diffraction data, obtained for an InSb/InGaSb/InSb/InAs superlattice grown on top of a GaSb buffer layer on a (001) GaSb substrate.

The Structural Characteristics of CIS Thin Films Prepared by Electro-Deposited Method

2013 ◽  
Vol 818 ◽  
pp. 88-91
Author(s):  
Kun Liu ◽  
Ji Sheng Yang ◽  
Rui Li ◽  
Wei Peng ◽  
Shi Pan
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Raman Spectroscopy ◽  
Raman Spectrum ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
Electro Deposition ◽  
X Ray ◽  
Micro Raman Spectroscopy ◽  
Deposition Technology

The properties of the absorber layer of solar cell CuInSe2(CIS) thin film made by electro-depostied method were researched in this article. Different concentration of reactant and voltage was applied to prepare the CIS film. The micro-Raman spectroscopy and X-ray diffraction (XRD) of CIS film was carried out. A correlation between the linewidth A1 mode of Raman spectrum and the XRD line and the voltage of electro-deposition technology was found.

Accuracy of linear polymer crystal structures determined from electron diffraction intensities: Problems with zonal data

1983 ◽  
Vol 41 ◽  
pp. 22-23
Author(s):  
Douglas L. Dorset
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Structural Information ◽  
Structure Refinement ◽  
Diffraction Theory ◽  
X Ray Diffraction ◽  
X Ray ◽  
Multidimensional Parameter ◽  
Unknown Structure ◽  
Refinement Process

In contrast to analyses based on X-ray and neutron diffraction intensity data, electron crystal structure determination for organic materials is only a crudely-developed procedure. Although the pioneering work of Vainshtein and co-workers has been very important for realization of the technique's advantages, self-consistent procedures based on earlier-derived diffraction theory have only recently emerged, enabling a reasonable estimate of what structural information might be obtained from a given microcrystalline organic specimen and how this might be best achieved. Problems which are unresolved include the optimal refinement procedure for an unknown structure and also the adequate identification of the correct crystal structure during this refinement process.The behavior of the crystallographic residual(R) during structure refinement is manifested by various minima in a multidimensional parameter space. The description of this space is more complicated for electron diffraction than for X-ray diffraction, although both cases include atomic position, atomic thermal vibration, atomic occupancy, “extinction”, and crystal distortion.

scholarly journals Enhancement of electrical properties of Al-doped ZnO thin films (AZO) by hydrogene plasma treatment

2013 ◽  
Vol 16 (4) ◽  
pp. 5-12
Author(s):  
Phuong Hoai Pham ◽  
Trung Kien Pham ◽  
Trung Quang Tran
Keyword(s):  
Thin Film ◽  
Plasma Treatment ◽  
Treatment Time ◽  
Structural Characteristics ◽  
Hydrogen Plasma ◽  
Wave Length ◽  
X Ray Diffraction ◽  
Electrical Stability ◽  
X Ray ◽  
Doped Zno

Transparent and conductive Al-doped ZnO (AZO) films were prepared by magnetron sputtering at temperature 200oC onto glass substrate. The films were treated with hydrogen plasma at temperatures 200oC from 30 to 60 minutes with 200 mW/cm2 power plasma. The optical, electrical and structural characteristics of the AZO coatings were analyzed as a function of the treatment time by spectrophotometry,Hall effects measurements, and X-ray diffraction. Results of X-ray diffraction analysis showed that the structure of the plasma-treated film did not change compared to that of the asdeposited film. The electrical resistivity of the AZO films decreased after H2 plasma treatment. The plasma treatment not only significantly decreased film resistivity but enhanced electrical stability as aging in air ambient. The average optical transmittance in the wave length range of 300 to 700 nm was 85%. These results were significant in application of AZO thin film as transparent electrode for a-Si:H based thin film solar cell prepared by PE-CVD method in next step.

Direct visualization of phase-separated domains in lipid membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 290-291
Author(s):  
S. W. Hui ◽  
T. P. Stewart
Keyword(s):  
Lipid Membranes ◽  
Structural Information ◽  
Freeze Fracture ◽  
Biological Molecules ◽  
Vacuum Drying ◽  
Direct Visualization ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Hydrocarbon Chains

Direct electron microscopic study of biological molecules has been hampered by such factors as radiation damage, lack of contrast and vacuum drying. In certain cases, however, the difficulties may be overcome by using redundent structural information from repeating units and by various specimen preservation methods. With bilayers of phospholipids in which both the solid and fluid phases co-exist, the ordering of the hydrocarbon chains may be utilized to form diffraction contrast images. Domains of different molecular packings may be recgnizable by placing properly chosen filters in the diffraction plane. These domains would correspond to those observed by freeze fracture, if certain distinctive undulating patterns are associated with certain molecular packing, as suggested by X-ray diffraction studies. By using an environmental stage, we were able to directly observe these domains in bilayers of mixed phospholipids at various temperatures at which their phases change from misible to inmissible states.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

X-ray diffraction properties of curved crystal diffractors

1992 ◽  
Vol 50 (2) ◽  
pp. 1734-1735
Author(s):  
W. Z. Chang ◽  
D. B. Wittry
Keyword(s):  
Diffraction Theory ◽  
X Rays ◽  
Diffraction Image ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Bent Crystal ◽  
Diffraction Geometry ◽  
Crystal Parameter ◽  
Quantitative Procedure

Since Du Mond and Kirkpatrick first discussed the principle of a bent crystal spectrograph in 1930, curved single crystals have been widely utilized as spectrometric monochromators as well as diffractors for focusing x rays diverging from a point. Curved crystal diffraction theory predicts that the diffraction parameters - the rocking curve width w, and the peak reflection coefficient r of curved crystals will certainly deviate from those of their flat form. Due to a lack of curved crystal parameter data in current literature and the need for optimizing the choice of diffraction geometry and crystal materials for various applications, we have continued the investigation of our technique presented at the last conference. In the present abstract, we describe a more rigorous and quantitative procedure for measuring the parameters of curved crystals.The diffraction image of a singly bent crystal under study can be obtained by using the Johann geometry with an x-ray point source.

Highlights in the history of X-ray topography1

1995 ◽  
Vol 210 (6) ◽  
Author(s):  
A. R. Lang
Keyword(s):  
Magnetic Domain ◽  
Diffraction Theory ◽  
Dislocation Loops ◽  
X Ray Diffraction ◽  
X Ray ◽  
Domain Structures ◽  
Structure Factors ◽  
History Of ◽  
Dislocation Sources ◽  
Non Destructive

AbstractX-ray topography provides a non-destructive method of mapping point-by-point variations in orientation and reflecting power within crystals. The discovery, made by several workers independently, that in nearly perfect crystals it was possible to detect individual dislocations by X-ray diffraction contrast started an epoch of rapid exploitation of X-ray topography as a new, general method for assessing crystal perfection. Another discovery, that of X-ray Pendellösung, led to important theoretical developments in X-ray diffraction theory and to a new and precise method for measuring structure factors on an absolute scale. Other highlights picked out for mention are studies of Frank-Read dislocation sources, the discovery of long dislocation helices and lines of coaxial dislocation loops in aluminium, of internal magnetic domain structures in Fe-3 wt.% Si, and of stacking faults in silicon and natural diamonds.

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