Papers by Author: Olga V. Feklisova

Abstract: Investigations of silicon layers grown on carbon foil were carried out using the Electron Beam Induced Current (EBIC) methods. The most of grain boundaries in these ribbons are (111) twin boundaries elongated along the direction. The EBIC measurements showed that the recombination contrast of dislocations and of the most part of twin boundaries at room temperature is practically absent and only random grain boundaries and very small part of twin boundaries produce a noticeable contrast. At lower temperatures a number of electrically active twin boundaries increases but the most part of them remains inactive. A contamination with iron increases the recombination activity of random boundaries but not the activity of twin boundaries.

Abstract: It is shown that the X-ray beam induced current method (XBIC) can be realized at the laboratory X-ray source using the polycapillary x-ray optics. The images of iron contaminated grain boundaries in multicrystalline Si are obtained. It is shown that the grain boundary XBIC contrast is 2-3 times smaller than the EBIC one. A simulation of XBIC and EBIC contrast values for two-dimensional defects is carried out and a good correlation between the experimental and calculated values is obtained. The dependence of grain boundary XBIC contrast on the X-ray beam width is calculated.

Abstract: Characterization of defect structure in silicon ribbon grown on carbon foil has been carried out. The structure of grown Si layers and a dislocation density in these layers have been studied using selective chemical etching and the Electron Backscattering Diffraction. It is observed that the layers consist of rather large grains, the majority of which is elongated along the growth direction with a similar surface orientation and with a misorientation angle between neighboring grains of 60º. This means that such grains are separated by the (111) twin boundaries. The dislocation density in different grains is found to vary from 102 to 107cm-2. The energy dispersive X-Ray microanalysis has shown that some twin boundaries are enriched with carbon.

Abstract: The Czochralski-grown silicon crystals plastically deformed at 680±C to the residual strain of 5% and subsequently annealed in the temperature range of 650{850±C were studied by the IR absorption and DLTS techniques. The formation and disappearance kinetics were investigated for several weak IR absorption lines around the 1000 cm¡1 wave number, which were previously related to the deformation-induced defects of non-dislocation nature in the dislocation trails. In parallel, the spectrum and concentrations of the deep-level centers in the upper half of the gap were measured by DLTS. It is found that the deep-level centers and op- tically active defects exhibit a common behavior during the post-deformation heat treatments. However, a direct correspondence between the IR and DLTS features cannot be established be- cause of the higher concentration of the deep-level centers as compared to the optically active defects.