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

Characterization of dislocations in germanium layers grown on (011)- and (111)-oriented silicon by coplanar and noncoplanar X-ray diffraction

Strained germanium grown on silicon with nonstandard surface orientations like (011) or (111) is a promising material for various semiconductor applications, for example complementary metal-oxide semiconductor transistors. However, because of the large mismatch between the lattice constants of silicon and germanium, the growth of such systems is challenged by nucleation and propagation of threading and misfit dislocations that degrade the electrical properties. To analyze the dislocation microstructure of Ge films on Si(011) and Si(111), a set of reciprocal space maps and profiles measured in noncoplanar geometry was collected. To process the data, the approach proposed by Kaganer, Köhler, Schmidbauer, Opitz & Jenichen [Phys. Rev. B, (1997 ▶), 55, 1793–1810] has been generalized to an arbitrary surface orientation, arbitrary dislocation line direction and noncoplanar measurement scheme

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

Residual stress state in oxide dispersive steel due to irradiation by swift heavy ions

Abstract. Oxide dispersive steel is a promising material for next nuclear reactors generation. Performance of this material in nuclear reactor can be modeled by means of irradiation by swift Bi ions, which are typical nuclear fusion products. Radiation damage results in microstructure alternation leading to formation of micro and macro stresses that influence the material performance. The residual stress state of ferrite matrix of the steel is investigated by XRD methodic and dependence on the irradiation dose is analyzed. Introduction Being considered as promising candidate materials for future reactors, oxide dispersion strengthened (ODS) steels are subject of extensive irradiation testing with various radiation sources. The dispersion of nano-sized oxides associated with the ferritic matrix confers very good creep strength at high temperature and resistance to radiation swelling at high dose Energetic ions can be used to investigate the effects of neutron irradiation in reactor components. Although the damage state depends on the particle type and damage rate, simulations with ion irradiations yield answer on basic mechanisms with the considerable advantage to enable easy variations of irradiation parameters without residual activity of the samples. In the last years, there have been considerable research efforts on development of ODS steels The addition of a small amount of Ti has been reported to be responsible for refinement of the dispersoid size In this paper we present the results of residual stress study of Fe-15Cr-2W-0.2Ti-0.35Y 2 O 3 ODS (KP123) steel irradiated with 700 MeV Bi ions

Residual stress state in oxide dispersive steel due to irradiation by swift heavy ions

Abstract. Oxide dispersive steel is a promising material for next nuclear reactors generation. Performance of this material in nuclear reactor can be modeled by means of irradiation by swift Bi ions, which are typical nuclear fusion products. Radiation damage results in microstructure alternation leading to formation of micro and macro stresses that influence the material performance. The residual stress state of ferrite matrix of the steel is investigated by XRD methodic and dependence on the irradiation dose is analyzed. Introduction Being considered as promising candidate materials for future reactors, oxide dispersion strengthened (ODS) steels are subject of extensive irradiation testing with various radiation sources. The dispersion of nano-sized oxides associated with the ferritic matrix confers very good creep strength at high temperature and resistance to radiation swelling at high dose Energetic ions can be used to investigate the effects of neutron irradiation in reactor components. Although the damage state depends on the particle type and damage rate, simulations with ion irradiations yield answer on basic mechanisms with the considerable advantage to enable easy variations of irradiation parameters without residual activity of the samples. In the last years, there have been considerable research efforts on development of ODS steels The addition of a small amount of Ti has been reported to be responsible for refinement of the dispersoid size In this paper we present the results of residual stress study of Fe-15Cr-2W-0.2Ti-0.35Y 2 O 3 ODS (KP123) steel irradiated with 700 MeV Bi ions

Long-range scans and many-beam effects for high-resolution x-ray diffraction from multilayered structures: Experiment and theory

A covariant matrix method based on many-beam dynamical x-ray diffraction is reported for simulation of the wide x-ray diffraction profiles from multilayered crystalline samples both in coplanar and noncoplanar geometries. Because of many-wave scattering, the approximations of the second-order on x-ray polarizability both for dispersion equations and boundary conditions are taken into account. The influence of various factors on calculation of the x-ray profiles containing multiple Bragg reflections is investigated

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

Stress of homogeneous and graded epitaxial thin films studied by full-shape analysis of high resolution reciprocal space maps

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 the sample. In the case of compositionally graded epitaxial films the situation is more complex since instead of a single Bragg peak there is a continuous diffracted intensity distribution which can be measured by means of recording high resolution reciprocal space maps. We analyse the thin film residual stress based not only on peak positions, but taking into account the defect-induced peak shape as well. Consideration of the peak shape enables the determination of the stress depth profile in the case of graded films and to imporves the accuracy in the case of homogeneous films