2. Articole

Permanent URI for this collectionhttps://msuir.usm.md/handle/123456789/47

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Author: search.filters.author.Evtodiev, IgorSubject: search.filters.subject.optical properties

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    SYNTHESIS AND OPTICAL PROPERTIES OF Ga2O3 NANOWIRES GROWN ON GaS SUBSTRATE
    (Elsevier, 2019) Leontie, L.; Sprincean, Veaceslav; Spaltu, N.; Cojocaru, A.; Susu, Ana; Lupan, Oleg; Vatavu, Elmira; Carlescu, Aurelian; Untila, Dumitru; Caraman, Iuliana; Evtodiev, Igor; Tiginyanu, Ion; Caraman, Mihail
    Gallium oxide (β-Ga2O3) nanowires were synthesized by heat treatment of single crystal β-GaS plates in air. Crystal structure and composition of synthesized materials were studied by X-ray diffraction, energy dispersive X-ray spectroscopy and Raman spectroscopy. Thermal treatment of β-GaS plates at 1023 K leads to the formation of a Ga2O3 (native oxide) layer on β-GaS (0001) surface of plates. Layer thickness and size of Ga2O3 wires contained were found to depend on temperature and duration of applied heat treatment. For 1023 K and 6 h, the length of Ga2O3 wires laid in the range from units to tens of nanometers, while for 1123 K and 30 min, between 30 and 40 μm.
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    OPTICAL AND PHOTOELECTRIC PROPERTIES OF NANOLAMELLAR STRUCTURES OBTAINED BY THERMAL ANNEALING OF InSe PLATES IN Zn VAPOURS
    (John Wiley & Sons, 2018) Untila, Dumitru; Evtodiev, Igor; Caraman, Iuliana; Spalatu, Nicolae; Dmitroglo, Liliana; Caraman, Mihail
    The structural, optical and photoelectric properties of InSe crystals grown by Bridgman–Stockbarger method and ZnSe/InSe structures obtained on InSe by thermal annealing in Zn vapours are studied in this paper. The study of structural properties confirms that ZnSe compound is formed. The analysis of photoelectric properties reveal that both the ZnSe‐InSe composite layer and the composite/InSe heterojunction are photosensitive in the VIS‐NIR spectral region. [ABSTRACT FROM AUTHOR]
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    OPTICAL PROPERTIES OF ZnO THIN FILMS OBTAINED BY HEAT TREATMENT OF Zn THIN FILMS ON AMORPHOUS SiO2 SUBSTRATES AND SINGLE CRYSTALLINE GASE LAMELLAS
    (Elsevier, 2016) Dmitroglo, Liliana; Evtodiev, Igor; Untila, Dumitru
    Optical absorption and photoluminescence of polycrystalline ZnO films obtained by thermal oxidation of Zn thin films deposited on amorphous SiO 2 (quartz) and (0001) surface of single crystalline GaSe lamellas have been investigated. The absorption edge of submicrometric ZnO films on quartz is determined by direct transitions corresponding to an optical band gap of 3.88 eV, at 300 K. For ZnO films with thickness between 1.5 and 10 μm, the absorption threshold is of excitonic nature. Photoluminescence of polycrystalline ZnO films on amorphous quartz reaches its maximum in the orange spectral range, while that of ZnO films on oriented single crystalline GaSe substrate covers the entire visible range. [ABSTRACT FROM AUTHOR]
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    STUDY OF RECOMBINATION MECHANISMS IN CRYSTALS GaSe DOPED WITH Cu, Cd AND Sn
    (2005) Evtodiev, Igor; Cuculescu, Elvira; Rusu, Marin; Caraman, Mihail
    The stratified crystals of GaSe type serve as the basic element in different optoelectronic devices such as the micro lasers (the excitation with the electron beam), optoelectronic modulators for a large domain of wavelengths [1]. In order to enlarge the domain of application of gallium monoselenium and of analogical compounds by the structure and physical mechanical properties (GaS and InSe) it is necessary to increase the variety of characteristic physical properties of these compounds. The studies of optical properties and photoelect rical ones of the crystals GaS, GaSe and InSe pure nondoped prove that on their base the optoelectronic devices can be elaborated for the visible range and the near IR. In order to reach the conquerable parameters with the existent elaborations (on the base of semiconductors AIIBVI, AIIIBVI) it is neessary to vary controllably with the diagram of localized states in the forbidden band of these crystals. It is known [2] that the impurity atoms in the crystals of GaSe type, after the liquidation of structural defects in the sub grid of the metal from the interior of stratified packages Hal-M-M-Hal are localized in the space among the planes of the neighbor packages contributing so to the increasing of cohesion force among packages. These atoms will be situated on the surface of cleaving on the direction perpendicular to C contri buting so to the formation of the ionized surface states. The physical properties of the extra fine monocrystalline films are modified by the surface states in which the characteristic properties of the structures with the reduced sizes are manifested.