L. V. Grigor’ev

Modification of zinc sulfide phosphors by irradiation with gamma-ray photons and electrons

The effect of γ-ray photons and electron beams on electroluminescence of the ZnS:(Cu, Br) and ZnS:(Cu, Al, Br) phosphors is studied. Irradiation of both samples with γ-ray photons and of the ZnS(Cu, Br) sample with electrons makes it possible to increase the emission intensity by 20–35% at the optimal radiation dose of 5–10 Mrad. In this case, the relative intensity of the green-emission band increases in the electroluminescence spectra of all samples, presumably due to dissociation of the CuI-CuZn and BrZn-VZn donor-acceptor pairs. Thus, irradiation makes it possible to control the intensity and spectrum of phosphors’ emission, which can be used for nonchemical lithography of luminescent layers.

Transport properties of thermally oxidized porous silicon

The process of current transfer in thermally oxidized porous silicon has been studied. A model based on the combination of hopping and tunneling mechanisms of charge transport is proposed. The concentration of charge traps and the mobility of charge carriers are evaluated using the current-voltage characteristics measured at 100 and 300 K.

Structural properties and current transport in a nanocomposite formed on a silicon surface by oxidation of the porous layer

The possibility of obtaining a Si-SiO2 nanocomposite layer by oxidation of porous silicon is demonstrated. The nanocomposite thus prepared consists of silicon oxide with inclusions of crystalline silicon in the form of rounded particles 5 to 30 nm in diameter and a filamentary cellular structure with filaments a few nanometers thick. The I-V characteristics of these structures were measured under different sample excitation conditions (photo-and thermal stimulation). The trap concentration and effective carrier mobility are estimated. Carriers are found to be captured intensely by traps created in the large-area interface in the composite structure.

Study of the structural and optical properties of thin polycrystalline zinc oxide films obtained by the ion-plasma method

This paper presents the results of a study of thin polycrystalline films of zinc oxide, created using the new Elion technology—ion-plasma sputtering of a metallic target in the medium of a powerful gaseous oxidant. It is shown that the ion-plasma method can be used to synthesize thin polycrystalline films of zinc oxide with optical properties close to those of single-crystal zinc oxide. The optical properties of thin polycrystalline zinc oxide films synthesized by the ion-plasma method can be used as a light–sound guide of thin-film acoustooptic devices that operate on the basis of surface acoustic waves or UV photodetectors.

Forming a silicon nanocomposite by laser annealing in a strong oxidant medium

This paper discusses the transmission spectra of a nanocomposite created by a new electron–ion technology—low-temperature laser surface modification of a layer of nanoporous silicon in a medium of a strong gaseous oxidant. A selective-absorption effect has been detected in the IR range. It is shown that the transmission spectrum of laser-oxidized nanoporous silicon has the form of a complex curve with four local minima, lying in the wavenumber ranges 4000–2750  cm−1, 2400–2100  cm−1, 1900–1600  cm−1, and 1300–1000  cm−1. A comparison of the transmission spectra of thermally oxidized nanoporous silicon and laser-modified nanoporous silicon in a strong oxidant atmosphere made it possible to explain the selective absorption of optical radiation in the nanocomposite thus created.

Laser-induced modification of porous silicon

We present the results of experiments on annealing the surface layer of porous silicon by pulsed IR laser radiation. The character of laser-induced modification has been studied using IR spectroscopy and transmission electron microscopy. It is shown that the proposed method can be used to obtain a Si:SiO2 composite.

Study of the optical and photoluminescence properties of nanostructured zinc oxide films obtained by the ion–plasma method

This paper presents the results of a study of the structural, optical, and photoluminescence properties of nanostructured zinc oxide films created by the method of ion–plasma sputtering of a metallic target at various gas pressures. It is shown that such zinc oxide films possess optical and photoluminescence properties close to those of single-crystal zinc oxide and can be used as a material for creating thin-film acoustooptic devices that operate on surface acoustic waves or for the receptor areas of UV photodetectors.

Investigating the energy spectrum of silicon nanoclusters in a silicon dioxide matrix

This paper presents the results of an investigation of the energy spectrum of traps that occur in a silicon nanocomposite created using the new “elion” technology—low-temperature laser modification of the surface of a layer of nanoporous silicon in the medium of a strong gaseous oxidant. Combined analysis of the transmission spectra of laser-oxidized nanoporous silicon and the trap-distribution function over the activation energy made it possible to explain the presence of selective absorption in the IR region.

Transport properties of a heterogeneous composite: Thermally oxidized silicon micropowder

The process of current transfer in a layer of composite material—thermally oxidized silicon micropowder on a silicon substrate—has been studied. A model based on the combination of hopping and tunneling mechanisms of charge transport is proposed. The concentration of charge traps and the mobility of charge carriers are evaluated using the current-voltage characteristics measured at 100 and 300 K in the dark and under illumination. The activation energies and frequency factors of the charge traps are determined.

Optical and photoluminescence properties of ytterbium-doped porous silicon subjected to laser-stimulated oxidation

This paper describes the results of creating a silicon composite doped with ytterbium ions, based on the process of laser-stimulated oxidation of a layer of porous silicon that contains ytterbium nitrate. It presents studies of the transmission spectra and photoluminescence spectra of a layer of ytterbium-ion-doped oxidized porous silicon. The transmission spectra show that the layer of porous silicon is oxidized when the laser acts on the surface of the porous silicon. The photoluminescence spectra demonstrate that ytterbium ions are present in the Yb3+ state. Results are presented of a study of the thermally activated conduction currents of the original porous silicon, of laser-oxidized porous silicon, and of a layer obtained by laser-stimulated oxidation of porous silicon that contains ytterbium nitrate. A comparative study is done of the transformation of the energy spectrum of traps, carried out in the process of laser-stimulated oxidation of a layer of porous silicon in the presence of ions of the rare-earth elements.