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.

Digital X-Ray Rocking Curve Topography

1986 ◽  
Vol 82 ◽  
Author(s):  
T. S. Ananthanarayanan ◽  
R. G. Rosemeier ◽  
W. E. Mayo ◽  
J. H. Dinan
Keyword(s):  
Bragg Reflection ◽  
Strain Tensor ◽  
Epitaxial Films ◽  
Double Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Density Maps ◽  
First Time ◽  
Considerable Body ◽  
Double Crystal Diffractometer

SUMMARYThere is a considerable body of work available illustrating the significance of X-ray rocking curve measurements in micro-electronic applications. For the first time a high resolution (100-150µm) 2-dimensional technique called DARC (Digital Autcmated Rocking Curve) topography has been implemented. This method is an enhancement of the conventional double crystal diffractometer using a real time 2-dimensional X-ray detector.Several materials have been successfully examined using DARC topography. Same of these include: Si, GaAs, AlGaAs, InGaAs, HgMnTe, Al, Inconel, steels, etc. By choosing the appropriate Bragg reflection multi-layered micro-electronic structures have been analyzed nondestructively. Several epitaxial films, including HgCdTe and ZnCdTe, grown by molecular beam epitaxy, have also been characterized using iARC topography. The rocking curve half width maps can be translated to dislocation density maps with relative ease. This technique also allows the deconvolution of the micro-plastic lattice strain ccaponent from the total strain tensor.

Defect structure analysis of polycrystalline materials by computer-controlled double-crystal diffractometer with position-sensitive detector

1983 ◽  
Vol 16 (1) ◽  
pp. 89-95 ◽  
Author(s):  
R. Yazici ◽  
W. Mayo ◽  
T. Takemoto ◽  
S. Weissmann
Keyword(s):  
Position Sensitive Detector ◽  
Polycrystalline Materials ◽  
Sensitive Detector ◽  
Double Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Local Lattice ◽  
Position Sensitive ◽  
The Individual ◽  
Double Crystal Diffractometer

The method represents an extension of a previously developed X-ray double-crystal diffractometer method when a film was used to record the crystallite reflections, each reflecting crystallite being regarded as the second crystal of a double-crystal diffractometer. By utilizing a position-sensitive detector (PSD) with interactive computer controls, the tedious and limiting task of data acquisition and analysis is greatly simplified. The specimen is irradiated with crystal-monochromated radiation and the numerous microscopic spots emanating from the reflecting crystallites are recorded separately by the position-sensitive detector and its associated multichannel analyzer at each increment of specimen rotation. An on-line minicomputer simultaneously collects these data and applies the necessary corrections. This process is then automatically repeated through the full rocking-curve range. The computer carries out the rocking-curve analysis of the individual crystallite reflections as well as that of the entire reflecting crystallite population. The instrument is provided with a specimen translation device which permits analysis of large sections of solid specimens. Thus, sites of local lattice defects induced either mechanically, chemically or by radiation can rapidly be established and quantitatively determined in terms of rocking-curve parameters as well as imaged by X-ray topography, by inserting a film in front of the PSD. The versatility and usefulness of the method is demonstrated by examples given from studies of fracture, fatigue and stress-corrosion cracking of commercial alloys.

Characterization of epilayers by X-ray double crystal rocking curve peak profile analysis

1995 ◽  
Vol 148 (1-2) ◽  
pp. 31-34 ◽  
Author(s):  
Haiyan An ◽  
Ming Li ◽  
Shuren Yang ◽  
Zhenhong Mai ◽  
Shiyong Liu
Keyword(s):  
Profile Analysis ◽  
Double Crystal ◽  
Rocking Curve ◽  
X Ray

Characterization of SiC Substrates Using X-Ray Rocking Curve Mapping

2006 ◽  
Vol 527-529 ◽  
pp. 729-732 ◽  
Author(s):  
Murugesu Yoganathan ◽  
Ejiro Emorhokpor ◽  
Thomas Kerr ◽  
A. Gupta ◽  
C.D. Tanner ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Lattice Distortion ◽  
Lattice Strain ◽  
Bragg Reflection ◽  
Sharp Change ◽  
Lattice Curvature ◽  
Rocking Curve ◽  
X Ray ◽  
Grain Misorientation

SiC substrates produced at II-VI, Inc. have been characterized using x-ray rocking curve mapping (topography). The rocking curves have been measured in the -scan mode for the (0006) Bragg reflection of 6H and the (0004) reflection of 4H SiC substrates. The maps contain information extracted from the rocking curves, such as the peak angle () and the rocking curve broadening (FWHM). In the case when lattice distortion is present due to the elastic or plastic deformation, the peak angle () changes gradually upon scanning, with the d/dx gradient proportional to the lattice curvature in the plane of diffraction. Multi-peak reflections and/or sharp change in the value of indicate the presence of misoriented grains. X-ray rocking curve mapping of SiC substrates yields excellent measures of crystalline quality that contain important information on the lattice strain and sub-grain misorientation.

scholarly journals All-diamond optical assemblies for a beam-multiplexing X-ray monochromator at the Linac Coherent Light Source

2014 ◽  
Vol 47 (4) ◽  
pp. 1329-1336 ◽  
Author(s):  
S. Stoupin ◽  
S. A. Terentyev ◽  
V. D. Blank ◽  
Yu. V. Shvyd'ko ◽  
K. Goetze ◽  
...  
Keyword(s):  
Light Source ◽  
Coherent Light ◽  
Rigid Substrate ◽  
Simultaneous Operation ◽  
Double Crystal ◽  
X Ray ◽  
Monochromator Crystal ◽  
Linac Coherent Light Source ◽  
Coherent Light Source

A double-crystal diamond (111) monochromator recently implemented at the Linac Coherent Light Source (LCLS) enables splitting of the primary X-ray beam into a pink (transmitted) and a monochromatic (reflected) branch. The first monochromator crystal, with a thickness of ∼100 µm, provides sufficient X-ray transmittance to enable simultaneous operation of two beamlines. This article reports the design, fabrication and X-ray characterization of the first and second (300 µm-thick) crystals utilized in the monochromator and the optical assemblies holding these crystals. Each crystal plate has a region of about 5 × 2 mm with low defect concentration, sufficient for use in X-ray optics at the LCLS. The optical assemblies holding the crystals were designed to provide mounting on a rigid substrate and to minimize mounting-induced crystal strain. The induced strain was evaluated using double-crystal X-ray topography and was found to be small over the 5 × 2 mm working regions of the crystals.

Fine-rotation attachment to standard goniometers

2004 ◽  
Vol 37 (1) ◽  
pp. 62-66 ◽  
Author(s):  
P. Suortti ◽  
J. Keyriläinen ◽  
M. Fernández
Keyword(s):  
Torsion Angle ◽  
Rotation Angle ◽  
Linear Actuator ◽  
Double Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Fine Focus ◽  
New Type ◽  
Rotation Stage ◽  
Double Crystal Diffractometer

A new type of fine-rotation stage has been constructed and tested. It can be attached to standard goniometers used in X-ray and neutron crystallography. The device consists of a shaft and a bar that is fitted tightly to a hole traversing the shaft. The diameter of the shaft is 5 to 10 times larger than the diameter of the bar and the length of the bar is about 5 times larger than the height of the shaft. The bottom of the shaft is attached to the top plate of the goniometer and a goniometer head can be fitted to the other end of the shaft. The free end of the bar is pushed tangentially by a linear actuator to produce a torsion moment at the shaft. The dimensions and materials of the prototype were chosen such that a 1 mm bend of the bar corresponded to a torsion angle of the shaft of about 20 µrad. The rotation angle was measured using a double-crystal diffractometer in the non-dispersive setting, with MoKα1radiation from a fine-focus X-ray tube. Accurately known angular deviations were produced by refraction in a prism and the shifts in the rocking-curve position were measured. The measured torsion angle agreed within 4% with the value calculated from the elastic constants and dimensions of the device. The repeatability of the angle was ±20 nrad (0.004 arcsec).

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