Simulation of X-ray topographs (original) (raw)
Related papers
Defect analysis in crystals using X-ray topography
Microscopy Research and Technique, 2006
A brief review of X-ray topography-a nondestructive method for direct observation and characterization of defects in single crystals-is presented here. The origin and development of this characterization method and the different techniques derived from it are described. Emphasis is placed on synchrotron X-ray topography and its application in studying various crystal imperfections. Mechanisms of contrast formation on X-ray topographs are discussed, with emphasis on contrast associated with dislocations. Determination of Burgers vectors and line directions of dislocations from analysis of X-ray topographs is explained. Contrast from inclusions is illustrated, and their differentiation from dislocations is demonstrated with the aid of simulated topographs. Contrast arising from the deformation fields associated with cracks is also briefly covered. Microsc. Res. Tech. 69:343-358, 2006.
Journal of Applied Crystallography, 2006
A technique, using a symmetric reflectionviaazimuthal rotation of a sample, is presented for characterization of the three-dimensional distribution of dislocations in single crystals. An analytic formula is derived to transform the three-dimensional geometry of a straight dislocation into its two-dimensional projection onto the detector plane. By fitting topographs to the formula, the orientations and locations of dislocations are quantitatively determined. The dislocations in a thermally stressed Si wafer are examined as an example.
Dislocation Contrast Analysis in Weak Beam Synchrotron X-Ray Topography
Materials Science Forum
Synchrotron monochromatic beam X-ray topography has been widely applied to characterize structural defects in SiC crystals. Using ray tracing simulations, the dislocation contrast in X-ray topography under strong diffraction conditions (diffraction takes place at or near Bragg angle) has been intensively investigated. However, the contrast and the configurations of the dislocation images recorded under weak diffraction conditions have not been fully investigated. Recently, we demonstrated that the contrast of dislocations in synchrotron grazing incidence topography under weak diffraction conditions can also be analyzed and interpreted by applying ray tracing principles. In this study, we have extended the application of the ray tracing method to analyze the dislocation contrast in weak beam synchrotron back reflection and rocking curve topography. The ray tracing method is shown to successfully simulate and correlate the contrast of threading screw dislocations at various positions ...
Comparison between the EBIC and XBIC contrasts of dislocations and grain boundaries
Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques, 2012
ABSTRACT The X-ray-beam-induced current (XBIC) method is used to calculate the contrasts of dislocations and grain boundaries perpendicular to a surface as a function of the diffusion length of minority charge carriers and the X-ray probe width. The results are compared with the contrasts of the same defects determined via the electron-beam-induced current (EBIC) techniques. It is demonstrated that the XBIC contrasts of grain boundaries and dislocations can be several times greater than those obtained in the EBIC mode in the case of a rather narrow X-ray beam. The XBIC contrast always exceeds that of EBIC in semiconductors with a large diffusion length even if the X-ray beam is rather wide.
A New X-ray Topographic Defect Contrast on Swept Quartz Crystals
X-ray topographic studies are made on vacuum-swept a-quartz crystals. A strong defect contrast is observed on X-ray topographs near the anode side of the crystal. This contrast disappears when the crystals are subjected to prolonged X-ray irradiation. The presence of this unusual contrast is attributed to lattice strains due to the collection of space charges near the anode side during vacuum sweeping. The negative space charge so formed is compensated by forming A1-OH and Al-hole centres during irradiation
Geometric determination of direction of dislocations using synchrotron X-ray transmission topography
Journal of Synchrotron Radiation, 2020
When performing transmission polychromatic beam topography, the extensions to the line segments of the diffraction images of a straight dislocation are shown to intersect at a single point on the X-ray film. The location of this point, together with the diffraction pattern recorded on the film by synchrotron radiation, gives the crystallographic direction [hkl] of the dislocation unambiguously. The results of two synchrotron topography experiments are presented. Very long dislocations found in the center of a large 450 mmdiameter Czochralski silicon crystal align with the growth direction [001]. In the other silicon sample, the dislocations are of mixed type and along the [011] direction.
X-ray topography in the study of semiconductors
X-ray topography as a completely nondestructive technique is frequently used to study crystal defects, deformation fields and compositional changes in semiconductors because of its high sensitivity to strains induced by defects in crystals. Principles of surface sensitive reflection Lang topography and reflection double crystal topography and their contrast mechanisms are shortly presented and three examples of their application given. The techniques have been used to characterize crystal defects such as threading dislocations arranged into cellular structure and slip bands at surfaces of semi-insulating GaAs substrate wafers, to characterize transformation of threading dislocations into misfit dislocations in a InGaAs/GaAs strained quantum well and to characterize misorientation domains in highly mismatched In-GaAs/GaAs heterostructures. In the last case tilt regions have been evidenced by synchrotron double crystal topography.
X-ray topography of subsurface crystal layers
Journal of Applied Crystallography
New capabilities of the Berg–Barrett topographic method are demonstrated using a skew-asymmetric X-ray diffraction scheme for investigating structural changes near the surface of semiconductor materials. Specifying the X-ray extinction depth, the details of defects and strains are revealed with high resolution. Consequently, analysis of structural distortion of layers near the surface after various types of surface processing becomes more complete.