Rocking-Curve Peak Shift in Thin Heterojunction Single Layers

1989 ◽  
Vol 145 ◽  
Author(s):  
C.R. Wie ◽  
Y-W. Choi ◽  
H.M. Kim ◽  
J.F. Chen ◽  
T. Vreeland ◽  
...  
Keyword(s):  
Thin Layer ◽  
Thick Layer ◽  
Diffraction Theory ◽  
Peak Shift ◽  
Peak Position ◽  
Thin Layers ◽  
Simple Method ◽  
Rocking Curve ◽  
X Ray ◽  
Layer Peak

AbstractA simple method for determining layer composition and mismatch of semiconductor hetero-epitaxial samples is by measuring the separation of peaks in x-ray rocking curve (XRC). This method fails if the peak separation is affected by other factors. For a small layer thickness, the layer peak position is affected by the x-ray amplitudes of the substrate or other thicker layers through the interference and overlap effects. In this case, a diffraction theory fitting process is necessary for a correct determination of layer parameters. We have used dynamical and kinematical x-ray diffraction theories to calculate the layer peak position as a function of its thickness for various layer/substrate combinations. These two theories yield substantially different results, indicating that the kinematical diffraction theory analysis is no longer valid for these thin layers. When a thick layer is present along with the thin layer, the thick layer is more influential than the substrate to the thin layer peak position, making the dynamical theory fitting necessary even from higher thickness.

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.

Mosaicity and Wafer Bending in SiC Wafers as Measured by Double and Triple Crystal X-Ray Rocking Curve and Peak Position Maps

2007 ◽  
Vol 556-557 ◽  
pp. 213-218 ◽  
Author(s):  
K.W. Kirchner ◽  
Kenneth A. Jones ◽  
Michael A. Derenge ◽  
Michael Dudley ◽  
Adrian R. Powell
Keyword(s):  
Laser Light ◽  
Peak Position ◽  
Etch Pit Density ◽  
Normal Position ◽  
Rocking Curve ◽  
X Ray ◽  
Etch Pit ◽  
Density Map ◽  
Beam Transmission ◽  
Si Wafer

Double and triple crystal rocking curve and peak position maps are constructed for a 4HSiC wafer for the symmetric (0 0 0 8) reflection in the normal position, the same reflection for a sample rotated 90º, and an asymmetric (1 23 6) reflection for the wafer in the normal position. These measurements were corrected for the ‘wobble’ in the instrument by scanning a 4” (1 1 1) Si wafer and assuming that the Si wafer was perfect and attributing the variations in the measurements to instrumental error. The x-ray measurements are correlated with a cross polar image, etch pit density map, white beam transmission x-ray topograph, and a laser light scan.

X-Ray Double Crystal Diffraction Characterization of Epitaxial Magnetic Transiton Metal Difluorides

1990 ◽  
Vol 187 ◽  
Author(s):  
M. Lui ◽  
A. R. King ◽  
V. Jaccarino ◽  
R. F. C. Farrow ◽  
S. S. P. Parkins
Keyword(s):  
Lattice Mismatch ◽  
Magnetic Transition ◽  
Diffraction Theory ◽  
Epitaxial Films ◽  
Structural Quality ◽  
Double Crystal ◽  
Lattice Match ◽  
Rocking Curve ◽  
X Ray ◽  
Quality Material

AbstractEpitaxial films of a variety of magnetic transition metal difluoride films have been grown by molecular beam epitaxy techniques. The structural quality of these films have been characterized using X-ray double crystal rocking curve analysis. The observed rocking curve linewidths were compared to their intrinsic values as calculated by dynamical diffraction theory. The degree of crystalline perfection as judge by the rocking curves have been correlated with the amount of lattice mismatch between the various epitaxial films and substrates. In the well lattice match case (Δa/a < 0.2%) of epitaxial films of FeF2 and CoF2 grown on (001) ZnF2 substrates, the rocking curve line widths approached their intrinsic limit indicative of extremely high quality material. This work represents some of the best epitaxial magnetic insulating films grown to date.

scholarly journals Large-surface-area diamond (111) crystal plates for applications in high-heat-load wavefront-preserving X-ray crystal optics

2016 ◽  
Vol 23 (5) ◽  
pp. 1118-1123 ◽  
Author(s):  
Stanislav Stoupin ◽  
Sergey Antipov ◽  
James E. Butler ◽  
Alexander V. Kolyadin ◽  
Andrey Katrusha
Keyword(s):  
Surface Area ◽  
Heat Load ◽  
Crystal Surface ◽  
High Heat ◽  
Peak Position ◽  
Large Surface Area ◽  
Crystal Optics ◽  
Rocking Curve ◽  
X Ray ◽  
High Heat Load

Fabrication and results of high-resolution X-ray topography characterization of diamond single-crystal plates with large surface area (10 mm × 10 mm) and (111) crystal surface orientation for applications in high-heat-load X-ray crystal optics are reported. The plates were fabricated by laser-cutting of the (111) facets of diamond crystals grown using high-pressure high-temperature methods. The intrinsic crystal quality of a selected 3 mm × 7 mm crystal region of one of the studied samples was found to be suitable for applications in wavefront-preserving high-heat-load crystal optics. Wavefront characterization was performed using sequential X-ray diffraction topography in the pseudo plane wave configuration and data analysis using rocking-curve topography. The variations of the rocking-curve width and peak position measured with a spatial resolution of 13 µm × 13 µm over the selected region were found to be less than 1 µrad.

Stress in Aluminium Alloys Measured Using Göbel Mirror as a Primary Beam Optics of X-Ray Diffractometer

2011 ◽  
Vol 681 ◽  
pp. 393-398 ◽  
Author(s):  
Marianna Marciszko ◽  
Andrzej Baczmanski ◽  
Nacer Zazi ◽  
Jean Paul Chopart ◽  
Alain Lodini ◽  
...  
Keyword(s):  
Aluminium Alloys ◽  
Grazing Incidence ◽  
Peak Position ◽  
Thin Layers ◽  
Incidence Geometry ◽  
Primary Beam ◽  
Beam Optics ◽  
Surface Layers ◽  
X Ray ◽  
Grazing Incidence Geometry

Grazing incidence geometry, called MGID-sin2y, was applied to measure surface stresses in very thin layers (depth of a few mm) of Al-Mg alloy samples subjected to different thermal and mechanical treatments. The Göbel mirror was used to parallelize the incident X-ray beam. Perfect collimation of the beam significantly increases accuracy of determined peak position and consequently allows to measure low stresses in surface layers.

Angular Corrections for the Seemann-Bohlin X-Ray Diffractometer

1991 ◽  
Vol 6 (4) ◽  
pp. 200-203 ◽  
Author(s):  
D. Rafaja ◽  
V. Valvoda
Keyword(s):  
Internal Standard ◽  
Correction Method ◽  
Lattice Parameter ◽  
Peak Position ◽  
Precise Determination ◽  
Thin Layers ◽  
X Ray ◽  
Diffraction Peaks ◽  
Steel Substrates

AbstractA method for the correction of peak position for the Seemann-Bohlin X-ray diffractometer, useful for practical application, is presented. The position of diffraction peaks is largely influenced by both the displacement of specimen from the diffractometer circle and the shift of the X-ray tube focus. The described correction method has been used for investigation of thin layers, especially for the precise determination of both lattice parameter and stresses in thin films. The application of the method is illustrated on samples of TiN and ZrN coatings deposited on steel substrates and additionally covered with a thin film of Si or Ta or TaC powder used as an internal standard.

scholarly journals Incorporation of interfacial roughness into recursion matrix formalism of dynamical X-ray diffraction in multilayers and superlattices

2017 ◽  
Vol 50 (3) ◽  
pp. 681-688 ◽  
Author(s):  
Ihar Lobach ◽  
Andrei Benediktovitch ◽  
Alexander Ulyanenkov
Keyword(s):  
Transition Layer ◽  
Iterative Scheme ◽  
Traditional Approach ◽  
Diffraction Theory ◽  
Matrix Formalism ◽  
X Ray Diffraction ◽  
Interfacial Roughness ◽  
Rocking Curve ◽  
X Ray ◽  
Sharp Interfaces

Diffraction in multilayers in the presence of interfacial roughness is studied theoretically, the roughness being considered as a transition layer. Exact (within the framework of the two-beam dynamical diffraction theory) differential equations for field amplitudes in a crystalline structure with varying properties along its surface normal are obtained. An iterative scheme for approximate solution of the equations is developed. The presented approach to interfacial roughness is incorporated into the recursion matrix formalism in a way that obviates possible numerical problems. Fitting of the experimental rocking curve is performed in order to test the possibility of reconstructing the roughness value from a diffraction scan. The developed algorithm works substantially faster than the traditional approach to dealing with a transition layer (dividing it into a finite number of thin lamellae). Calculations by the proposed approach are only two to three times longer than calculations for corresponding structures with ideally sharp interfaces.

A 4 Crystal Monochromator for High Resolution Rocking Curves

1987 ◽  
Vol 31 ◽  
pp. 403-408
Author(s):  
Robert W. Green
Keyword(s):  
Bragg Reflection ◽  
Thin Layers ◽  
Double Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Lattice Constants ◽  
Monochromator Crystal ◽  
Parallel Configuration ◽  
Double Crystal Diffractometer

X-ray characterization of single crystal materials in the form of thin layers can be accomplished with the use of a double crystal diffractometer. The resultant rocking curve is a convolution of the Bragg reflection from both the first and second crystals. The width of the rocking curve at half-height is a measure of the crystal perfection of a materiel. Since the FWHM for the material being analyzed cannot be less than that of the first crystal (Monochromator), the first crystal should be of very good crystal quality. The problem that arises with the two crystal parallel configuration (Fig. 1) is that the monochromator crystal must be changed each time a material of different orientation or stoichiometry with different resultant lattice constants is analyzed. This requires changing the monochromator and re-aligning the double crystal diffractometer.

X-ray diffraction from one-dimensionally disordered 2H crystals undergoing solid state transformation to the 6H structure. I. The layer displacement mechanism

1980 ◽  
Vol 369 (1739) ◽  
pp. 435-449 ◽  
Keyword(s):  
Diffraction Theory ◽  
Peak Shift ◽  
Exact Expression ◽  
X Ray Diffraction ◽  
State Transformation ◽  
Solid State Transformation ◽  
X Ray ◽  
Displacement Mechanism ◽  
Close Packed Structure ◽  
Integrated Intensity

The 2H or AB. . . close-packed structure may be transformed to 6H or ABCACB. . . structure if layer displacement faults occur preferentially on every third close-packed layer. The theory of X-ray diffraction from one-dimensionally disordered crystals undergoing the 2H → 6H structural transformation by such a layer displacement mechanism is developed. It is shown that it is necessary to consider that the faults do not occur entirely at random but prefer to occur at three-layer separations from each other in order to statistically create a 6H structure. The diffraction theory, as developed by earlier workers for 2H crystals containing a completely random distribution of stacking faults, cannot therefore be applied to the present case. An exact expression for the diffracted intensity from crystals undergoing the 2H → 6H transformation has been obtained and the different observable diffraction effects (like change in integrated intensity, peak shift, integral breadth, peak asymmetry) have been predicted.

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