Papers by Author: E.V. Kolesnikova

Abstract: Scanning transmission electron microscopy (STEM) in combination with electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) have been used to investigate Si+-implanted amorphous silicon dioxide layers and the formation of Si nanoclusters. The microstructure of the Si doped silica films was studied by energy filtered transmission electron microscopy (EFTEM) in a 200 kV FEI Tecnai F20 TEM. The samples were amorphous, thermally grown 500 nm SiO2 layers on Si substrate doped by Si+ ions with an energy of 150 keV up to an atomic dopant fraction of about 4 at%. A thermal post-annealing leads to formation of silicon clusters with sizes 1-5 nm and concentrations of about 1018 cm-3. Respective cathodoluminescence spectra in the near IR region indicate such structural changes by appearance of an additional band at 1.35 eV as well as additional emission bands in the visible green-yellow region.

Abstract: Defects distribution in 6H-SiC implanted with Bi ions was investigated with the local cathodoluminescence. There are two typical areas with radiation defects found in implanted samples. Implanted layer was about 27 micrometers depth. Far-action area with radiation defects was observed for the first time. Thickness of this area varies from few tens up to hundreds micrometers. This effect depended on concentration of defects i.e. irradiation fluence. Radiation defects at this area disappeared after annealing the sample if fluence is not to high.

Abstract: Structural features of 4H-SiC structures with CVD epitaxial layers, subjected to high-dose Al ion implantation and short high-temperature pulse annealing, have been studied using secondary-ion mass-spectroscopy, transmission electron spectroscopy, local cathodoluminescence and cathodoluminescence imaging on cross-sectionally cleaved surfaces of the structures. An accelerated diffusion of radiation defects, a “long-range action effect”, with a diffusion coefficient of 10 -9 cm2 s-1 after high-dose Al ion implantation and the gettering effect after subsequent pulsed thermal annealing have been observed for the first time. After a short high-temperature annealing, the quality of the starting material is improved in the course of formation of implantation-doped p+-n junctions due to defect gettering. As a result of the decrease in the concentration of optical active defect centers as well of deep centers by an order of magnitude in CVD layer, an increase in the diffusion length of minority carriers (Lp) by a factor of 1.5-2 was obtained.

Abstract: During interaction between thin film SiO2 and electron beam with high power density, amorphous silicon dioxide modifies. Silicon nanoclusters are formed in radiated area. Result of this interaction is formation of Si/SiO2 nanocomposite. We studied modified SiO2 by TEM, microdiffraction and cathodoluminescence.