Epitaxial strain in multilayered heterostructures (thin films and core-shell nanostructures) has been intensely investigated as a fundamental way to tailor the properties of various functional materials, such as ferroelectrics, magnetics, superconductors as well as to create new multifunctional materials. Upconversion is a strain-sensitive luminescence process, in which the strain plays a critical role through distorting the local crystallographic environment of the luminescent atom. However, the majority of the research on the effect of stain on upconversion focuses on the core-shell nanostructures synthesized by wet-chemical methods, where the strain imposed by misfit of core and shell compositions is generally low (<1%). The Core-shell structure becomes unstable under greater strain. To investigate the effect of a significantly higher strain in upconversion materials, we grew epitaxial Y2O3:Yb,Er films, in which the out-of-plane strain could reach similar to 1.3% even with the thickness above 300 nm, without breaking the epitaxial ordering. The upconversion spectra reveal that the highly strained thin films of upconversion materials have the tendency to facilitate the multi-photon excitation, illuminating a novel method for the design of upconversion materials with large anti-Stokes shift.

An avalanche silicon photodiode has been developed for the near IR, visible, UV and VUV light ranges. The external quantum efficiency has been studied in the 114–170 and 210–1100 nm ranges. It has been demonstrated that the avalanche photodiode reaches the quantum yield of 29 to 9300 electrons/photon at the 160 nm wavelength and bias voltage of 190–303 V, respectively.

Avalanche silicon photodiode have been developted for near ir, visible, UV and VUV light range. External quantum efficiency have been studied in 114 - 170 abd 210 - 1100nm range. It is demonstrated that photodiode reach from 29 to 9300 electrons/photon on 160 nm with bias voltage of 190 and 303 v respectively.

Effect of the pump power on the photoluminescence intensity for dislocation-related luminescence centers is studied in p-type silicon containing oxygen precipitates. Oxygen precipitates are induced as a result of three-stage annealing used for formation of a getter for fast diffusing impurities in microelectronics technology while D1 and D2 dislocation-related luminescence centers were produced during subsequent annealing in a flow of argon at 1000oC. The photoluminescence excitation efficiencies for the D1 and D2 lines were measured at a temperature of liquid helium. Keywords: dislocation-related luminescence, silicon, oxygen precipitates, photoluminescence excitation efficiency.

Effect of the pump power on the photoluminescence intensity for dislocation-related luminescence centers is studied in p-type silicon containing oxygen precipitates. Oxygen precipitates are induced as a result of three-stage annealing used for formation of a getter for fast diffusing impurities in microelectronics technology while D1 and D2 dislocation-related luminescence centers were produced during subsequent annealing in a flow of argon at 1000°С. The photoluminescence excitation efficiencies for the D1 and D2 lines were measured at a temperature of liquid helium.

The possibilities of medium (hundreds of keV) energy ion beams usage for solid state PIXE diagnostics is examined. The method modification, consisting in the utilizing of neutral beams as the probe, is proposed. It is shown, that transition to such beams makes it possible to exclude the negative influence of effects, caused by the appearance of the surface potential due to charge accumulation in case of insulating samples study.

The external quantum yield of silicon avalanche photodiode in the wavelength range of 120-170 nm was performed. It was shown that the engineered avalanche photodiode has the external quantum yield of 24-150 electron/proton under reverse bias voltage of 230-345 V, respectively. The testing of worked out avalanche photodiode by means of pulse flash of 280 and 340 nm wavelength demonstrates the speed, corresponding to the bandwidth not less than 25 MHz.

We have designed a silicon avalanche photodiode for detecting vacuum ultraviolet radiation. The external quantum yield of a silicon avalanche photodiode has been investigated in the wavelength range of 120–170 nm. It is shown that the avalanche photodiode has an external quantum yield of 24–150 electrons/photons at a reverse bias voltage of 230–345 V. Testing of this avalanche photodiode with pulsed illumination at wavelengths of 280 and 340 nm has shown performance corresponding to a transmission band no narrower than 25 MHz.

The concentration profiles of defects produced in structures upon the implantation of nitrogen ions into GaAs epitaxial layers with an uncovered surface and that covered with an AlN film and subsequent annealing are studied. The ion energies and the implantation doses are chosen so that the nitrogen-atom concentration profiles coincided in structures of both types. Rutherford proton backscattering spectra are measured in the random and channeling modes, and the concentration profiles of point defects formed are calculated for the samples under study. It is found that the implantation of nitrogen ions introduces nearly the same number of point defects into structures of both types, and the formation of an AlN film by ion-plasma sputtering is accompanied by the formation of an additional number of defects. However, the annealing of structures of both types leads to nearly the same concentrations of residual defects.

The influence exerted by the conditions of the post-implantation annealing of silicon implanted with germanium ions on how luminescence centers are formed is studied. Measurements by the technique of the Rutherford backscattering of medium- and high-energy ions demonstrates that implantation with 1-MeV germanium ions at a dose of 1.5 × 1014 cm–2 does not lead to the amorphization of single-crystal silicon. It is found that subsequent high-temperature annealing of the implanted samples in a chlorine-containing atmosphere at a temperature of 1100°C for 0.5–1.5 h gives rise to so-called D1 and D2 dislocation-related luminescence lines with wavelengths of 1.54 and 1.42 μm. With increasing annealing duration, the intensity of the D1 line decreases and that of D2 remains constant, but the D1 line dominates in all the spectra. The possible factors responsible for a decrease in the intensity of the D1 line and, in particular, the diffusion of germanium atoms and the formation of a silicon–germanium solid solution are discussed.

AbstractThe concentration profiles of defects produced in structures upon the implantation of nitrogen ions into GaAs epitaxial layers with an uncovered surface and that covered with an AlN film and subsequent annealing are studied. The ion energies and the implantation doses are chosen so that the nitrogen-atom concentration profiles coincided in structures of both types. Rutherford proton backscattering spectra are measured in the random and channeling modes, and the concentration profiles of point defects formed are calculated for the samples under study. It is found that the implantation of nitrogen ions introduces nearly the same number of point defects into structures of both types, and the formation of an AlN film by ion-plasma sputtering is accompanied by the formation of an additional number of defects. However, the annealing of structures of both types leads to nearly the same concentrations of residual defects.

The implantation of Czochralski-grown p-type silicon with 1-MeV germanium ions at a dose of 2.5 × 1014 cm–2 does not lead to the amorphization of single-crystal silicon. Under subsequent high-temperature annealing, electrically active acceptor centers are transformed. Their concentration and special distribution depend on the annealing temperature. The possible factors determining how these centers are formed are discussed.

AbstractThe influence exerted by the conditions of the post-implantation annealing of silicon implanted with germanium ions on how luminescence centers are formed is studied. Measurements by the technique of the Rutherford backscattering of medium- and high-energy ions demonstrates that implantation with 1-MeV germanium ions at a dose of 1 . 5 × 10^14 cm^–2 does not lead to the amorphization of single-crystal silicon. It is found that subsequent high-temperature annealing of the implanted samples in a chlorine-containing atmosphere at a temperature of 1100°C for 0.5–1.5 h gives rise to so-called D1 and D2 dislocation-related luminescence lines with wavelengths of 1.54 and 1 . 42 μm. With increasing annealing duration, the intensity of the D1 line decreases and that of D2 remains constant, but the D1 line dominates in all the spectra. The possible factors responsible for a decrease in the intensity of the D1 line and, in particular, the diffusion of germanium atoms and the formation of a silicon–germanium solid solution are discussed.

AbstractThe implantation of Czochralski-grown p -type silicon with 1-MeV germanium ions at a dose of 2 . 5 × 10^14 cm^–2 does not lead to the amorphization of single-crystal silicon. Under subsequent high-temperature annealing, electrically active acceptor centers are transformed. Their concentration and special distribution depend on the annealing temperature. The possible factors determining how these centers are formed are discussed.

The initial stages of growth of barium zirconate titanate and barium stannate titanate ferroelectric films on single-crystal sapphire and silicon carbide are studied for the first time. The choice of substrates is dictated by the possibility of using such structures in ultra-high frequency devices. The growth of discontinuous BaZrxTi1–xO3 films is found to be mediated by the gas phase mass transport mechanism in the studied temperature range. For deposition of BaSnxTi1–xO3 films, the mechanism of mass transport switches at ~800°C from surface diffusion to gas phase diffusion; also, the films deposited on sapphire and silicon carbide have considerably different elemental composition. The formation of an intermediate SiO2 layer is noted on silicon carbide during the growth of oxide films on this substrate, its thickness depending on the deposition temperature.

AbstractThe medium-energy ion scattering (MEIS) spectroscopy was used to obtain the data on the structure and stoichiometry of interfaces in LaAlO_3/SrTiO_3 (LAO/STO) heterostructures. The coverage of the LAO/STO heterostructure with a LAO film increased by a factor of almost two as the lanthanum aluminate layer thickness increased from 1 to 6 unit cells. It is shown that the formation of the heterostructure is accompanied by the interchange with Sr ions of the substrate and La ions of the firm. The influence of the oxygen pressure on the formation of the heterostructure has been studied. The conditions required to form nanodimentional interlayer of a quasi-two-dimensional electron gas with high mobility of electrons in the interface region are analyzed.

Comparison of the channel spectra of medium energy ion scattering, visualized for LaAlO3/(001)SrTiO3 heterostructures with a thickness of the lanthanum aluminate layer of one to six unit cells, indicates that the lanthanum aluminate layer grows coherently on a TiO2-terminated surface of a strontium titanate substrate. The resistance of the interphase boundary in the heterostructure with a thickness of the LaAlO3 layer of six unit cells decreased with temperature. At T < 100 K, the positive magnetoresistance and Hall mobility of electrons increased sharply with decreasing temperature.

AbstractThe initial stages of growth of barium zirconate titanate and barium stannate titanate ferroelectric films on single-crystal sapphire and silicon carbide are studied for the first time. The choice of substrates is dictated by the possibility of using such structures in ultra-high frequency devices. The growth of discontinuous BaZr_ x Ti_1– x O_3 films is found to be mediated by the gas phase mass transport mechanism in the studied temperature range. For deposition of BaSn_ x Ti_1– x O_3 films, the mechanism of mass transport switches at ~800°C from surface diffusion to gas phase diffusion; also, the films deposited on sapphire and silicon carbide have considerably different elemental composition. The formation of an intermediate SiO_2 layer is noted on silicon carbide during the growth of oxide films on this substrate, its thickness depending on the deposition temperature.

Secondary-ion mass spectrometry and Rutherford proton backscattering have been used to measure the concentration profiles of nitrogen atoms and examine the defect structure of epitaxial GaAs layers implanted with 250-keV N+ ions at doses of 5 × 1014–5 × 1016 cm–2. It was found that no amorphization of the layers being implanted occurs at doses exceeding the calculated amorphization threshold, a concentration of point defects that is formed is substantially lower than the calculated value, and a characteristic specific feature of the defect concentration profiles is the high defect concentration in the surface layer.

The medium-energy ion scattering (MEIS) spectroscopy was used to obtain the data on the structure and stoichiometry of interfaces in LaAlO 3 /SrTiO 3 (LAO/STO) heterostructures. The coverage of the LAO/STO heterostructure with a LAO film increased by a factor of almost two as the lanthanum aluminate layer thickness increased from 1 to 6 unit cells. It is shown that the formation of the heterostructure is accompanied by the interchange with Sr ions of the substrate and La ions of the firm. The influence of the oxygen pressure on the formation of the heterostructure has been studied. The conditions required to form nanodimentional interlayer of a quasi-two-dimensional electron gas with high mobility of electrons in the interface region are analyzed.