Surface morphology of DyxOy films grown on Si

The crystalline structure and surface morphology of DyxOy dielectric films grown on Si substrates were studied by grazing incidence diffraction and absorption with use of synchrotron radiation and by atomic force microscopy. The crystalline structure and the roughness of DyxOy films were found to be strongly dependent on the deposition rate. The dielectric-silicon interface depends on the type of gas used in the annealing process. Moreover. results from the near edge X-ray absorption studies, have revealed that none of the examined films has a stoichiometry close to the Dy2O3. The level of stoichiometry is determined by the technological conditions. Nevertheless, MOS structures with Dy(x)Q(y) films (EOT similar to 23 angstrom) have shown a rather good DyxOy-Si interface properties, which can be further improve by thermal annealing, and introducing of several additives, therefore DyxOy films can be considered as suitable candidates for gate dielectric in MOS devices. (c) 2006 Elsevier B.V. All rights reserved

Point defects and p-type conductivity in Zn1-xMnxGeAs2

Positron annihilation spectroscopy is used to study point defects in Zn1–xMnxGeAs2 crystals with low Mn content 0≤x≤0.042 with disordered zincblende and chalcopyrite structure. The role of negatively charged vacancies and non-open-volume defects is discussed with respect to the high p-type conductivity with carrier concentration 10exp19≤p≤10exp21cm−3 in our samples. Neutral As vacancies, together with negatively charged Zn vacancies and non-open-volume defects with concentrations around 10exp16−10exp18 cm−3, are observed to increase with increasing Mn content in the alloy. The observed concentrations of defects are not sufficient to be responsible for the strong p-type conductivity of our crystals. Therefore, we suggest that other types of defects, such as extended defects, have a strong influence on the conductivity of Zn1–xMnxGeAs2 crystals.Peer reviewe

Study of ultrathin Pt/Co/Pt trilayers modified by nanosecond XUV pulses from laser-driven plasma source

We have studied the structural mechanisms responsible for the magnetic reorientation between in-plane and out-of-plane magnetization in the (25 nm Pt)/(3 and 10 nm Co)/(3 nm Pt) trilayer systems irradiated with nanosecond XUV pulses generated with laser-driven gas-puff target plasma source of a narrow continuous spectrum peaked at wavelength of 11 nm. The thickness of individual layers, their density, chemical composition and irradiation-induced lateral strain were deduced from symmetric and asymmetric X-ray diffraction (XRD) patterns, grazing-incidence X-ray reflectometry (GIXR), grazing incidence X-ray fluorescence (GIXRF), extended X-ray absorption fine structure (EXAFS) and transmission electron microscopy (TEM) measurements. In the as grown samples we found, that the Pt buffer layers are relaxed and that the layer interfaces are sharp. As a result of a quasi-uniform irradiation of the samples, the XRD, EXAFS, GIXR and GIXRF data reveal the formation of two distinct layers composed of Pt1-xCox alloys with different Co concentrations, dependent on the thickness of the as grown magnetic Co film but with similar ∼1% lateral tensile residual strain. For smaller exposure dose (lower number of accumulated pulses) only partial interdiffusion at the interfaces takes place with the formation of a tri-layer composed of Co-Pt alloy sandwiched between thinned Pt layers, as revealed by TEM. The structural modifications are accompanied by magnetization changes, evidenced by means of magneto-optical microscopy. The difference in magnetic properties of the irradiated samples can be related to their modification in Pt1-xCox alloy composition, as the other parameters (lateral strain and alloy thickness) remain almost unchanged. The out-of-plane magnetization observed for the sample with initially 3 nm Co layer can be due to a significant reduction of demagnetization factor resulting from a lower Co concentration

Occurrence of the fungi from the genus Ampelomyces – hyperparasites of powdery mildews (Erysiphales) infesting trees and bushes in the municipal environment

The studies refer to the phenomenon of hyperparasitism in the municipal environment. The paper presents the occurrence of fungi of the genus Ampelomyces on Erysiphales – important group of phytopathogenic fungi. For the first time in Poland analyzed degree of infestation of Erysiphales mycelium by Ampelomyces and effect of the hyperparsites on the degree of infestation plants by Erysiphales. The high participation of the Ampelomyces was noted in each year of the study. Substantial differences were noted in the occurrence of Ampelomyces depending on the developmental stage of the host fungi and considerable differences in the prevalence of the hyperparasites on particular Erysiphales species. In all cases examined, the mean index of infestation of host plants by Erysiphales was higher than the mean degree of infestation of powdery mildew mycelium by Ampelomyces. The results indicate that under natural conditions they do not play any significant role in the reduction of the degree of infestation of host plants by Erysiphales and do not disturb drastically their life cycle

X-Ray Study of Synthetic Alunite

Synthetic alunite was obtained by two different synthesis methods. Powder data obtained with a standard Bragg-Brentano geometry of two analyzed samples are reported for a broad angular range. The chemical analysis as well as the unit-cell dimensions indicate that the analyzed alunite is K and Al deficient and contains excess water. A need for high resolution diffraction experiments is expressed

High Pressure - High Temperature Diffraction Study of MnTe Using Synchrotron Radiation

High pressure — high temperature experiments for MnTe of NiAs typewere performed using a synchrotron radiation as X-ray source and a cubicanvil X-ray diffraction press to produce nonambient sample environment.In the investigated range of pressure (0-67.5 kbar) on uploading and withfollowing temperature rise from 296 to 1273 K (at 67.5 kbar), the struc-ture type of MnTe is conserved. An earlier reported nonlinear behaviour oflattice-parameter c0 is not found in the present study. Possible reasons ofthis discrepancy are discussed. The vałue of bułk modulus and its pressurederivative were calculated from the pressure—volume dependence by fittingthe Birch—Murnaghan equation