Bunches of misfit dislocations on the onset of relaxation of Si0.4_{0.4}Ge0.6_{0.6}/Si(001) epitaxial films revealed by high-resolution x-ray diffraction

The experimental x-ray diffraction patterns of a Si$_{0.4}$Ge$_{0.6}$/Si(001) epitaxial film with a low density of misfit dislocations are modeled by the Monte Carlo method. It is shown that an inhomogeneous distribution of 60$^\circ$ dislocations with dislocations arranged in bunches is needed to explain the experiment correctly. As a result of the dislocation bunching, the positions of the x-ray diffraction peaks do not correspond to the average dislocation density but reveal less than a half of the actual relaxation

Characterization of SiGe thin films using a laboratory X-ray instrument

The technique of reciprocal space mapping using X-rays is a recognized tool for the nondestructive characterization of epitaxial films. X-ray scattering from epitaxial Si0.4Ge0.6 films on Si(100) substrates using a laboratory X-ray source was investigated. It is shown that a laboratory source with a rotating anode makes it possible to investigate the material parameters of the super-thin 2–6 nm layers. For another set of partially relaxed layers, 50–200 nm thick, it is shown that from a high-resolution reciprocal space map, conditioned from diffuse scattering on dislocations, it is possible to determine quantitatively from the shape of a diffraction peak (possessing no thickness fringes) additional parameters such as misfit dislocation density and layer thickness as well as concentration and relaxation

Calculation of X-ray stress factors using vector parameterization and irreducible representations for SO(3) group

Abstract. In the presence of texture, the concept of X-ray elastic constants as well as Sin 2 ψ law is inapplicable and the X-ray stress factors (XSF) connecting average strain and stress have to be used [1-2]. The SO(3) vector parameterization with smart composition la

Boron doped cubic silicon probed by high resolution X-ray diffraction

Highly boron doped epitaxial silicon, with boron concentrations well above 1x1020 cm-3, is of great interest for applications in large variety of electronic and photonic devices where it is used as a low resistivity contact. The Bragg peak position of a homogeneous solid solution epitaxial film is directly related to the solid solution concentration, film strain and, consequently residual stress. The peak shape contains information about defects present in an epilayer. Here we report structural experiments performed at room temperature and atmospheric pressure on a set of boron doped Si thin epilayers grown on a Si(001) substrate. We analyzed the BSi epilayers using high resolution X-ray rocking curve, reflectivity measurements and high resolution reciprocal space mapping (HR-RSM). The measurements were carried out by Rigaku SmartLab diffractometer

Fisher information for optimal planning of X-ray diffraction experiments

Fisher information is a powerful mathematical tool suitable for quantification of data `informativity' and optimization of the experimental setup and measurement conditions. Here, it is applied to X-ray diffraction and an informational approach to choosing the optimal measurement configuration is proposed. The core idea is maximization of the information which can be extracted from the measured data set by the selected analysis technique, over the sets of accessible reflections and measurement geometries. The developed approach is applied to high-resolution X-ray diffraction measurements and microstructure analysis of multilayer samples, and its efficiency and consistency are demonstrated with the results of more straightforward Monte Carlo simulations

Microstructure Characterization of Multilayer Thin Coatings ZrN/Si 3 N 4 by X-Ray Diffraction Using Noncoplanar Measurement Geometry

International audienceThe structural characterization of multilayer thin coatings is performed by X‐ray diffraction using a noncoplanar measurement geometry. The application of such a measurement geometry enables a reliable and comprehensive microstructural analysis of the material comparing to other measurement geometries due to the accessibility to a larger number of measured Bragg reflections. The important advantage of noncoplanar geometry is a measurement setup without tilting and rotating the sample. A set of profiles for different Bragg reflections is measured for several multilayer coatings with different thicknesses of individual layers; the obtained profiles are combined into a single scan for the simultaneous fittingby a theoretical curve. The broadening of the diffraction profiles is considered to be affected by a small grain size and instrumental effects, with the grains being modeled by ellipsoidal shape with two equal in‐plane axes. Based on the proposed fitting procedure, the microstructural parameters of multilayer coatings are evaluated, including the grains size in parallel and normal to the surface directions. The dependence of evaluated grains size on the measurement direction confirms the validity of the selected grains model. The microstructural parameters evaluated from noncoplanar X‐ray diffraction show a good agreement with those obtained from HRTEM and STEM techniques