Papers by Author: M.V. Zamoryanskaya

Abstract: The aim of this work is study of point defects modification in silicon dioxide by a high power density electron beam. In this work we used the method which allows to estimate quantitative content of luminescent point defects by dependence of cathodoluminescence on current density. Content of point defects was evaluated and changing of point defect content in silicon dioxide under electron beam was assessed. It is shown that content of defect connected with silicon deficit decreases whereas content of defect connected with oxygen deficit increases. The model of point defects transformation was suggested on the basis of these results.

Abstract: GaSb based III-V heterostuctures are attractive for optoelectronic devices such as midin- frared lasers, detectors, and thermophotovoltaics (TPVs). In this paper the growth and characterization of GaInAsSb and GaAlAsSb quaternary layers, lat-tice-matched to GaSb substrate, are reported, with a particular focus on these alloys for TPV devi-ces. High-quality with a mirror-like surface morphology epilayers Ga1-x InxAsy Sb1-y with In content x in the range 0.1-0.22 and Ga1-xAlxAsySb1-y layers with Al content up to 0.3 in the solid are grown by Liquid-Phase Epitaxy (LPE) from In- and Ga-rich melt, respectively. The compositions of the quaternary compounds are determined by X-ray microanalysis. The crystalline quality of GaInAsSb/ GaSb and GaAlAsSb/GaSb heterostuctures is studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements.

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: In this paper the new method for determination of luminescent centers concentration are discussed. While the possibility of electron traps determination and definition of its activation energy are suggested. The cathodoluminescent (CL) method was used. The determination of luminescent centers concentration in silicon oxide is based on the measurements of dependences of CL intensity on electron beam current. The presence and energy of activation of electron traps were studied by measurement of rise time and decay of luminescent band during the stationary irradiation of silica by electron beam.

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: The local cathodoluminescence is used to study the point defects and their depth distribution in silicon oxide and silicon. The defects formed by two-coordinate silicon (Si=Si), oxygen vacancies (Si-Si, Si-Si-Si), non-bridgen oxygen (-O.), amorphous silicon and silicon nanoclusters have characteristic emission bands. High sensibility of cathodoluminescence method permits to study natural silicon oxide film, thin silicon oxide and silicon layers near the interface. In this paper an influence of the silicon type on the properties of SiO2/Si interface is discussed. It is shown that the quality of SiO2/Si interface depends not only on the technology process but on the silicon type and activator concentration. A high boron content in silicon leads to an increase of point defects concentration in silicon oxide and sometimes to an appearance of Si nanoclusters near the interface in the layer with 10-20 nm thickness. The concentration of intrinsic defects near the silicon oxide – n-silicon interface depends also on phosphorous concentration. But in this case low concentration of activator leads to a presence of high content of intrinsic defects in the first monolayers of silicon oxide and to a dramatical decrease of a content of these defects in films with thickness of more that 10 nm. On the contrary, the high concentration of activators leads to low content of intrinsic defects near the interface and a rise of its content in the film with thickness more that 10 nm.

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.

Abstract: In this work we studied the cathodoluminescence (CL) of thin silicon oxide and natural silicon oxide grown on different types of silicon substrates (p-silicon and n-silicon with different content of boron and phosphor). At the same time we studied the distribution of intrinsic defects on depth for thermal silicon oxide films with depth resolution 10-20 nm. The method of local cathodoluminescence was used for definition the structure defects in SiO2 think layer and control of the quality of SiO2-Si interface.