Search

We study the kinetics of the photovoltage decay in silicon crystals, caused by the effect of lowenergy (E = 8 keV) X-ray radiation. A correlation between radiation-induced changes in the short-term and long-term components of the photovoltage decay and the charge state of the surface, determined by measuring the surface distribution of the amplitude and decay time of the photovoltage, is found.

Features of changes in the microhardness of nand p-type Si crystals exposed to low-energy X-ray radiation (E = 8 keV) at low doses (D = 1.8 × 103 to 3 × 104 Gy) are studied. The changes are classified as a radiation–mechanical effect and depend on a number of factors, e.g., layer occurrence depth, siliconcrystal conductivity type, and charge-carrier concentration. The revealed difference in the radiation–mechanical effects in nand p-type Si crystals is attributed to the specific features of radiation-stimulated interdefect transformations in the studied crystals.

The crack resistance of silicon samples with copper coatings has been studied at room temperature. It has been shown that the deposition of copper coatings on the silicon surface is accompanied by an increase in the crack resistance factor and the formation of regions with dislocations in external load zones, which indicates plastic deformation in the brittle fracture zone.

The effect of soft X-rays with photon energy W = 8 keV on the kinetics of decay photovoltage in solar silicon crystals is studied. The correlation between the radiation-stimulated change in the electrical characteristics of the investigated crystals and the evolution of their charge, structural state, and surface morphology is established. Also studied are the changes in the photovoltage decay kinetics caused by the action of X-rays on the solar Si – nanofilled polymer coating structures. It is shown that X-ray irradiation leads to quite big recombination losses in the case that the epoxy-urethane matrix contains a filler (polysiloxane particles (PSPs)) in the amount of 0.001 and 1.0 wt. %. At the same time, at PSP filler content of 0.5 wt. %, the passivation epoxy-urethane coatings exhibit an increased radiation resistance.

The possibility of magnetic ordering at dangling bonds in dislocation cores has been investigated theoretically. It has been experimentally shown that magnetic ordering in dislocations affects the spin-dependent effects occurring in dislocation crystals of silicon. It has been found that preliminary magnetic treatment of silicon crystals in a weak magnetic field leads to the suppression of the electroplastic effect induced in silicon crystals excited by an electric current. It has been assumed that a change in the microplasticity under the combined action of a magnetic field and an electric current is caused by a weakening of spin-dependent recombination at dislocation dangling bonds.

The effect of a weak permanent magnetic field on the structure and charge state of silicon for solar-power engineering is investigated. It is revealed that magnetostimulated changes in the defect-impurity state and surface potential have a reversible character.

The effect of low-energy (W = 8 keV) low-dose ((0.3–7.3) × 102 Gy) radiation and a dc magnetic field (B = 0.17 T) on structural, micromechanical, and microplastic characteristics of silicon crystals has been studied. The features in the dynamic behavior of dislocations in silicon crystals, which manifest themselves upon only X-ray exposure and combined (X-ray and magnetic) exposure, have been revealed.

The effect of chemical treatment of porous silicon samples by HF on its photoluminescence and its evolution with time in sample aging in air is investigated. It is shown that the effect of HF on the luminescence parameters depends on the duration of the treatment and the initial photoluminescence intensity of the sample. It is found that chemical etching in HF accelerates the growth of the total luminescence intensity in aging of the sample in air. The evolution of the photoluminescence spectrum in aging of the sample in air after chemical etching can be explained within the framework of the quantum-size model of the luminescence of porous silicon.

We carry out a comparison between the luminescence spectra (photo-and x-ray luminescence) of porous silicon and disperse SiO2, which by its physical characteristics is most similar to oxide films on porous silicon. The photoluminescence of porous silicon was also investigated using fluorescence (excitation by a nitrogen laser) and metallographic microscopes. We found that the natures of the luminescence centers of porous silicon and disperse SiO2 are identical. A porous layer on single-crystal silicon ensures the creation of a highly branched surface of oxide film. Luminescence centers are located on its inner (as viewed from the porous silicon) surface.

The analysis of spectral luminescence characteristics of disperse Si02 indicates the presence of two types of surface oxygen vacancies (O-VI and O-VII). Their concentrations can be decreased by means of near UV and IR laser irradiation. It is established that the O-V concentration decreasing under IR irradiation (λirr = 1064 nm) in air is caused by their laser annealing under seven-photon ionization of surface O-V with the participation of atomic oxygen formed near the surface under dissociation of atmospheric 02 molecules in the laser field. The irradiation by near UV laser light (λirr ~250-360 nm) leads to a lower effective O-V concentration with decreasing IR irradiation. The analysis of the dose dependence shows that in this case the observed effect is due to the interaction of surface O-V with bulk reagents (water, OH− groups, 02 centers) or their photolysis products, not with atmospheric oxygen. The choice of laser irradiation wavelength is important for selective effect on O-VI and O-VII c...

The inorganic molecular ions (UO 2 2+ , CrO 4 2- ), together with the linear and nonlinear optical methods were used to study of the disperse SiO2 surface adsorption activity. Selective laser excitation of the luminescence spectra of uranyl ions adsorbed on SiO2 surface allowed investigations to be made of the adsorption properties for different active centers on the surface. The adsorption properties of the self-defects active centers have been investigated by means of the luminescent characteristics of the Chromate anions under multiphoton resonant excitation with subsequent ionization and dissociation of the CrO 4 2- anions. The second harmonic generation for a pure and modified sorbents was used to investigation of the formation and destruction dynamics of the self-defects active centers.