Zinātniskie raksti (CFI) / Scientific articles

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Browsing Zinātniskie raksti (CFI) / Scientific articles by Author "Akilbekov, A."

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    Ab-Initio Calculations of Oxygen Vacancy in Ga2O3 Crystals
    (Sciendo, 2021) Usseinov, A.; Koishybayeva, Zh.; Platonenko, Aleksandrs; Akilbekov, A.; Purans, Juris; Pankratov, Vladimir; Suchikova, Y.; Popov, Anatoli I.
    Gallium oxide β-Ga2O3 is an important wide-band gap semiconductor. In this study, we have calculated the formation energy and transition levels of oxygen vacancies in β-Ga2O3 crystal using the B3LYP hybrid exchange-correlation functional within the LCAO-DFT approach. The obtained electronic charge redistribution in perfect Ga2O3 shows notable covalency of the Ga-O bonds. The formation of the neutral oxygen vacancy in β-Ga2O3 leads to the presence of deep donor defects with quite low concentration. This is a clear reason why oxygen vacancies can be hardly responsible for n-type conductivity in β-Ga2O3.--//-- Licenced under CC BY 4.0.
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    Accumulation of radiation defects and modification of micromechanical properties under MgO crystal irradiation with swift 132Xe ions
    (Elsevier B.V., 2020) Baubekova, G.; Akilbekov, A.; Feldbach, E.; Grants, Rolands; Manika, Ilze P.; Popov, Anatoli I.; Schwartz, K.; Vasil'Chenko, Evgeni A.; Zdorovets, Maxim V.; Lushchik, Aleksandr Ch
    Accumulation of F-type defects under irradiation of MgO crystals by 0.23-GeV 132Xe ions with fluence varying by three orders of magnitude has been investigated via the spectra of optical absorption and low-temperature cathodoluminescence. The number of single centers continuously increases with fluence without any marks of saturation. At the highest fluence, a mean volume concentration of 3.1 × 1019 and 3.35 × 1019 cm−3 is reached for F and F+ centers, respectively. The F+ emission strongly dominates in the cathodoluminescence of irradiated MgO and its enhancement with fluence is detected. However, the creation efficiency of the F2 aggregate centers is very low and fluence dependence has a complicated shape. Radiation-induced changes of micro-mechanical properties of the same samples have been analysed; the depth profiles of hardening correlate with the ion energy loss. A joint contribution of ionization and impact mechanisms in the formation of structural defects under MgO irradiation with Xe ions is considered.