| 1. |
- Elhag, Sami, et al.
(författare)
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Low-temperature growth of polyethylene glycol-doped BiZn2VO6 nanocompounds with enhanced photoelectrochemical properties
- 2017
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Ingår i: Journal of Materials Chemistry A. - Cambridge : Royal Society of Chemistry. - 2050-7488. ; 5:3, s. 1112-1119
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate scalable, low-cost and low-temperature (<100 °C) aqueous chemical growth of bismuth–zinc vanadate (BiZn2VO6) nanocompounds by BiVO4 growth on ZnO nanobelts (NBs). The nanocompounds were further doped with polyethylene glycol (PEG) to tune the electronic structure of the materials, as a means to lower the charge carrier recombination rate. The chemical composition, morphology, and detailed nanostructure of the BiZn2VO6 nanocompounds were characterized. They exhibit rice-like morphology, are highly dense on the substrate and possess a good crystalline quality. Photoelectrochemical characterization in 0.1 M lithium perchlorate in carbonate propylene shows that BiZn2VO6 nanocompounds are highly suitable as anodes for solar-driven photoelectrochemical applications, providing significantly better performance than with only ZnO NBs. This performance could be attributed to the heterogeneous catalysis effect at nanocompound and ZnO NB interfaces, which have enhanced the electron transfer process on the electrode surface. Furthermore, the charge collection efficiency could be significantly improved through PEG doping of nanocompounds. The photocurrent density of PEG-doped BiZn2VO6 nanocompounds reached values of 2 mA cm−2 at 1.23 V (vs. Ag/AgCl), over 60% larger than that of undoped BiZn2VO6 nanocompounds. Photoluminescence emission experiments confirmed that PEG plays a crucial role in lowering the charge carrier recombination rate. The presented BiZn2VO6 nanocompounds are shown to provide highly competitive performance compared with other state-of-the art photoelectrodes.
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| 5. |
- Semchuk, OY, et al.
(författare)
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Laser-surface nanostructures in carbon coating
- 2005
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Ingår i: Fullerenes, nanotubes, and carbon nanostructures. - : Taylor and Francis. - 1536-383X .- 1536-4046. ; 13, s. 331-337
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we propose a theoretical basis of a new method of Laser Ablation Lithography (LAL) using coherent laser beams interference patterns. The advantage of our method is the absence of the need to use a mask. In our method the profile of nanostructures surface in carbon coating is produced by an interference laser beam pattern and depends on the following parameters: angle of beams convergence, phase difference, and intensity of the beams, and so forth.
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| 6. |
- Semchuk, OY, et al.
(författare)
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Wave function and quasi-energy of conduction electrons in a field of coherent light beams
- 2004
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Ingår i: Physica status solidi. B, Basic research. - : John Wiley andamp;amp; Sons, Ltd. - 0370-1972 .- 1521-3951. ; 241:11, s. 2549-2554
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Tidskriftsartikel (refereegranskat)abstract
- In this work the influence of high-frequency coherent light beams (CLB) on the motion of conduction electrons in a crystalline phase is studied. The wave function and the quasi-energy of conduction electrons are calculated. It is shown that a force that is associated with a pressure from the CLB influences the conduction electrons. A new approach to construct the kinetic equation, that takes into account the effects due to a CLB field that acts as the elementary processes for quasi-particle interaction in a crystalline phase, is presented.
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| 7. |
- Semchuk, O. Yu., et al.
(författare)
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Features of coherent laser beams interaction with condensed matter
- 2004
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Ingår i: Appl. Surf. Sci.. - : Elsevier BV. - 0169-4332. ; 234:1-4, s. 415-421
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Tidskriftsartikel (refereegranskat)abstract
- Some mechanisms of formation of laser-induced periodic surface and bulk structures in condensed matter are considered. Their influence on optical properties of semiconductors is investigated. It is shown that under action of coherent laser beams (CLBs) a grating of the refraction index arises in semiconductors. The models featuring this effect are offered. The relevant theoretical calculations confirming occurrence the new phenomenon — appearance of a grating of the refractive index in semiconductors in a field of CLBs — were carried out. It is shown that in ferromagnetic semiconductors (FMSC) with a laser-induced grating of the magnon temperature one probably deals with occurrence of the nonlinearity of the refraction index caused by the nonlinearity of FMSC magnetic susceptibility and one should observe oscillations of a refraction index, which will result in occurrence of complementary darkened areas.
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| 8. |
- Semchuk, O. Yu., et al.
(författare)
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Features of transport phenomenas in magnetic semiconductors with laser-induced periodic nanostructures
- 2007
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936 .- 0928-4931 .- 1873-0191. ; 27:5-8, s. 1360-1363
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms of formation of the laser-induced periodic surface and bulk nanostructures in magnetic semiconductors are considered. Their influence on transport phenomena in ferromagnetic semiconductors (FMSC) is investigated. It is shown that under action of laser beams (LB) a laser-induced periodic nanostructures — gratings of the electron and magnon temperatures, electron concentration and electric fields arises in FMSC. It is determined, that the illuminating of an external surface of the FMSC by several LB results in an emerging new effect — appearance of a dropping site on the voltage-current characteristic (VCC) of the FMSC with the static laser-induced periodic nanostructures. This effect can only be observed for the carrier concentration n ≥ 1018 cm−3, since for smaller concentration the contribution of an additional current caused by the presence of the laser-induced periodic nanostructures will be insignificant.
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| 9. |
- Semchuk, O. Yu, et al.
(författare)
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Laser ablation lithography on thermoelectric semconductor
- 2006
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 252:13, s. 4759-4762
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, experimental results of the investigation of the periodic structure on thermoelectric semiconductor Cu2Se are presented. Periodic structures were formed on surfaces of semiconductors due to multi-beam interaction of Q-switched Nd:YAG laser, which was operated in the lowest order of Gaussian mode and pulse duration 7 ns. Surface temperature evolution and transient reflectivity are studied during laser treatment. Creation of Cu islands in the maximal intensity of interference pattern was found.
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| 10. |
- Semchuk, O. Yu., et al.
(författare)
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Thermal effects caused by action of powerful laser radiation on condensed matter
- 2010
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Ingår i: JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS. - : Inoe and Infm. - 1454-4164. ; 12:3, s. 586-588
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Tidskriftsartikel (refereegranskat)abstract
- The spatial and temporal temperature distribution on a solid's surface heated by laser interference pattern is calculated using integral transformation on coordinates x, y and Fourier transformation on coordinate z . Two-dimensional periodic structure consisting of circles with radii equal to a radius of the laser beam is considered. It is shown, that the maximal heating is observed in the center of a circle while diminishing to periphery. The area where the intensive surface heating is observed extends up to 0.8 r/a ( a is a period of the grating, r is a radius of the laser beam).
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