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Doping silicon nanocrystals (SiNCs) provides a new way to modify their luminescence properties and tailor them for a particular application. We prepared Li-doped SiNCs and characterized them by neutron depth profiling and x-ray diffraction. Our SiNC samples are doped with around 10-100 Li atoms per one nanocrystal and their lattice slightly expands after lithium insertion. We show that the photoluminescence (PL) properties of Li-doped SiNCs are distinctly modified compared to the undoped case. The PL maximum shifts to shorter wavelengths and the PL decay time decreases, both these features being favorable for applications in photonics. The spectral blue-shift is attributed to the tensile strain in SiNCs induced by doping with lithium. [ABSTRACT FROM AUTHOR]

In this article, we combine diffuse x-ray scattering with a Monte Carlo simulation method for the determination of the dislocation density in thin heteroepitaxial layers. As a model, we consider GaN epitaxial layers containing threading dislocations perpendicular to the surface. The densities of particular types of threading dislocations following from the comparison of measured and simulated distributions of diffusely scattered x-ray intensity are compared with the dislocation densities determined by etching. A good agreement was found. [ABSTRACT FROM AUTHOR]

An x-ray method is described for the structure characterization of semiordered GaN nanorods. In contrast to other works based on synchrotron radiation, the method uses a standard x-ray laboratory equipment so that it is suitable for a rapid characterization of the nanorods in a technological laboratory. The method uses a grazing-incidence diffraction setup and it makes it possible to determine the mean size of the rods and their angular twist with respect to the crystalline substrate. The applicability of the method is demonstrated on a series of GaN nanorod samples and the parameters of the nanorods are compared with the results of scanning electron microscopy. [ABSTRACT FROM AUTHOR]

The intensity of x-ray diffraction from a polycrystalline multilayer in a grazing-incidence scattering geometry is modulated by a standing wave created by the interference of the radiation transmitted through the multilayer stack with the wave field specularly reflected from the superlattice interfaces. Similarly, the radiation being diffracted from the polycrystalline structure is reflected specularly from the interfaces and a standing-wave interference pattern results as well. This effect is demonstrated by a series of diffraction measurements on C/Ni periodic multilayers; the experimental data have been modeled using the distorted-wave Born approximation and a very good correspondence with the experiments was achieved. The method was used for the study of the profiles of the crystallite sizes and strains in multilayers. [ABSTRACT FROM AUTHOR]

Continuous downscaling of complementary metal-oxide semiconductor devices requires the manufacture of highly doped ultrashallow junctions. A preamorphizing implant (PAI) is commonly used in industrial processing in order to avoid unfavorable profile broadening and channeling tails during dopant atom implant in the ultralow energy regime (<5 keV). In this work, we report about a detailed characterization of the structural changes induced by xenon PAI treatment on ultralow energy arsenic-implanted (001) silicon. Combined x-ray scattering methods, medium energy ion scattering, and transmission electron microscopy are applied to obtain as comprehensive picture as possible of the reordering processes occurring during the postimplantation annealing treatment. Evidence is found that end-of-range defects, present after implant below the amorphous-to-crystalline interface, transform from small Si interstitial clusters to dislocation loops during annealing depending on the implant conditions. Simultaneously, As atoms redistribute by moving to the substitutional sites of the freshly regrown Si lattice without inducing a local residual strain field. The remaining fraction of electrically inactive dopants cumulates in a subnanometer-thick layer beneath the surface oxide. [ABSTRACT FROM AUTHOR]

A simple approach for the analysis of mosaic epitaxial layers is proposed, based on a Patterson-like analysis of the reciprocal-space distribution of the scattered intensity. Within this approach, the mosaic-block-shape function P and the deformation correlation function are determined. The method is used for the analysis of relaxed PbTe epitaxial layers on Si(111). The sizes of the mosaic blocks determined by this method are compared with the results of conventional Williamson-Hall-type analyses of the width of the diffraction maxima. The block sizes compare well with the mean distances of threading dislocations penetrating the PbTe layers. [ABSTRACT FROM AUTHOR]

Coplanar high-resolution x-ray diffraction has been used for the characterization of size, chemical composition, and strain of Ge/Si (001) islands in a three-dimensional island crystal grown using self-assembly on a prepatterned (001) Si substrate. The measured diffusely scattered intensity is simulated using the kinematical approximation and the parameters of model islands are fitted. These simulations require calculations of the strain fields within the islands and the spacer layers. For this purpose, an analytical approach to solve the continuum elasticity equations has been extended to a full three-dimensional calculation. The Ge content in the islands is found to be on the average 40%, and the island shape does not change dramatically during capping. [ABSTRACT FROM AUTHOR]

Lateral composition modulation in InAs/AlAs short-period superlattices was investigated by x-ray grazing-incidence diffraction and coplanar x-ray diffraction at a “normal” wavelength and at an anomalous wavelength, for which diffraction from the (200) planes does not exhibit a chemical contrast. The experimental data were compared with theoretical simulations assuming that the interfaces consist of a periodic sequence of monoatomic steps. The displacement field in the superlattice was calculated by continuum elasticity and using a valence-force field method. From the fit of the experimental data to the theory, the lengths of individual atomic terraces were determined. [ABSTRACT FROM AUTHOR]

We have studied the interface morphology of SiGe/Si multilayers by means of specular and nonspecular x-ray reflectivity under grazing incidence. The samples were grown by molecular beam epitaxy on silicon substrates with (001) surface orientation and with different directions of the surface misorientation. X-ray reflectivity measurements in different azimuths are compared to data from atomic force microscopy, which are used to simulate the x-ray experiments. With this combination of experimental techniques we have determined the structural properties, in particular the ordering of different features present at the sample surface and inside the multilayer at the SiGe/Si layer interfaces. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents information on a study wherein a theory describing x-ray diffuse scattering from misfit dislocations in epitaxial layers was developed. Methods; Results; Discussion.

Provides information on a study which investigated the use of a high-temperature multicrystal X-ray diffractometer for the measurement of elastic constants and the thermal-expansion coefficient of a heteroepitaxial ZnTe layer grown on a (001) oriented GaAs substrate. Function of a triple-crystal method; Reason behind the need to grow ZnTe layers on GaAs substrates; Occurrence of the relaxation of lattice mismatch.

Presents a study that described x-ray diffraction in thin layers containing small randomly placed defects by means of the kinematical diffraction theory and optical coherence formalism. Calculation of both the diffracted intensity and angular distribution; simulation of double crystal and triple crystal x-ray diffractometry experiments; Application of the theory to experimental data obtained from diffractometry measurements of an epitaxial zinc-tellurium layer with mosaic structure.

Presents a study which investigated a surface defect-free denuded zone in silicon wafers using x-ray double-crystal diffractometry. Comparison of the thickness values obtained by the method with results from chemical etching of wafer cross sections; Difference in the mean lattice parameter of the defect region and of the zone; Formula for the intensity of the wave diffracted by a crystal with a denuded zone.