Browsing by Author "Kantser, Valeriu"

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CRYSTALLINE STRUCTURE AND PHOTOLUMINESCENCE OF GaSe-CdSe NANOCOMPOSITE
(2015) Dmitroglo, Liliana; Evtodiev, Igor; Caraman, Iuliana; Kantser, Valeriu; Untila, Dumitru; Stamate, Marius; Gasin, Petru
A material consisting of CdSe and GaSe crystallites with average dimensions of 34 nm and 30 nm respectively was obtained by heat treatment at 753K and 853K of GaSe single crystal plates in Cd vapors during 24 hours. As a result of Cd atoms interaction with Se atoms CdSe layers are formed both onto outer surface and at interface of layered Se-Ga-Ga-Se packages. CdSe crystallites on the surface grow in the form of plates along C6 crystallographic axis. Photoluminescence spectra of the composite, at 78K and 300K, contain predominant bands from the luminescent emission of GaSe and CdSe components.
GROWTH AND CHARACTERIZATION OF Eu DOPED GaSe SINGLE CRYSTALS BY X-RAY DIFFRACTION AND RAMAN SPECTROSCOPY
(CEP USM, 2017) Untila, Dumitru; Evtodiev, Igor; Caraman, Iuliana; Kantser, Valeriu; Spalatu, Nicolae; Dmitroglo, Liliana; Evtodiev, Silvia; Spoială, Dorin; Rotaru, Irina; Gașin, Petru
GaSe single crystals doped with Eu (0.025, 0.05, 0.5, 1.0 and 3.0 at%) were grown by Bridgman method using Ga, Se and Eu elementary components. The crystalline structure and vibration modes of the GaSe: Eu crystals lattice were studied by X-ray diffraction and Raman spectroscopy. Eu atoms arranged in the van der Waals space of GaSe: Eu crystals form Eu-Se valence bonds and restructure hexagonal lattice of GaSe leading to EuGa2Se4 crystallites formation. Defects generated by EuGa2Se4 crystallites lead to broadening and shifting of single phonon peaks present in Raman spectra towards shorter wavenumbers, and at the same time, activate the longitudinal optical vibrations of EuSe sublattice.
A NEW APPROACH TO THE TESTING OF ICE-FORMING AEROSOLS IN CLOUD ENVIRONMENTS
(Editura "Tehnica-UTM", 2015-05-20) Zasavitsky, E.; Kantser, Valeriu; Sidorenko, Anatolie; Belenchuk, Alexandr; Shapoval, Oleg M.; Chirita, Arcady
The elaborated method allows tracking the dynamics of the process in climate chamber under impact of the ice-forming reagent. Simultaneous registration of cloud transmittance and recording of the ice forming process gives us an integral picture of AgI reagent effect on testing cloud. In this study we find a positive correlation between testing cloud transmission and ice particle formation. We showed that count of ice particles and determination of its density and size is possible directly in climate chamber as well as dynamics of particles deposition.
PHOTOLUMINESCENCE OF NANOCOMPOSITES OBTAINED BY HEAT TREATMENT OF GaS, GaSe, GaTe AND InSe SINGLE CRYSTALS IN Cd AND Zn VAPOR
(2016) Evtodiev, Igor; Caraman, Iuliana; Kantser, Valeriu; Untila, Dumitru; Rotaru, Irina; Dmitroglo, Liliana; Evtodiev, Silvia; Caraman, Mihail
The photoluminescence (PL) spectra of GaS, GaSe, GaTe and InSe semiconductors used as the basis materials to obtain nanocomposite by heat treatment in Zn and Cd vapor were studied. The PL spectra of ZnS–GaS, CdSe– GaSe, CdSe–InSe, ZnSe–InSe composites consist of wide bands covering a wide range of wavelengths in the antistokes region for CdSe, ZnSe and GaS crystallites from composites. The antistokes branches of spectra are interpreted as the shift of PL bands to high energies for nanosized crystallites.
STRUCTURAL AND OPTICAL PROPERTIES OF COMPOSITES CONTAINING A III B VI AND A II B VI SEMICONDUCTORS
(2017) Evtodiev, Igor; Untila, Dumitru; Evtodiev, Silvia; Caraman, Iuliana; Gasin, Petru; Dmitroglo, Liliana; Rotaru, Irina; Kantser, Valeriu
By thermal annealing of InSe, GaSe, and GaTe crystals in Zn vapors at 800, 870, and 1050K, respectively, a material consisting of ZnSe crystallites in both GaSe and InSe and ZnTe in GaTe has been prepared. Structural defects induced by intercalated atoms shield excitonic bonds in primary compounds and form both radiative recombination levels and electron trapping levels localized deep in the band gap of AIIIBVI crystals. The energies of trapping levels have been determined from thermally stimulated luminescence curves.
STRUCTURE AND OPTICAL PROPERTIES OF GaSe - CdSe COMPOSITES DRIVEN BY Cd INTERCALATION IN GaSe LAMELLAR CRYSTALS
(2015) Caraman, Iuliana; Kantser, Valeriu; Evtodiev, Igor; Leontie, Liviu; Arzumanyan, Grigory; Untila, Dumitru; Dmitroglo, Liliana
A new composite material composed of GaSe and CdSe has been obtained by treatment of GaSe single-crystal lamellas in Cd vapors at temperatures of 773 853 K and intercalation of Cd interlayers. The struc ture and optical properties of the GaSe-CdSe composite material have been studied. The content of CdSe crystallites was found to grow with increasing treatment temperature or with increasing duration of treatment at a constant temperature. Analysis of XRD, PL, XPS, AFM, and Raman patterns has shown that the heterogeneous composite composed of micro and nanocrystallites of CdSe in GaSe can be obtained by Cd intercalation in a temperature range of 753 853 K. On the basis of Raman spectrum, the vibrational m odes of the composite have been identified. The PL of these materials contains emission bands of free and bound excitons, donor - acceptor bands, and bands of recombination via impurity levels. The PL emission spectra measured at a temperature of 78 and 300 K for the composites result from the overlapping of the emission bands of the components of GaSe doped with Cd and the CdSe crystallites .
STRUCTURE AND OPTICAL PROPERTIES OF GaSe-CdSe COMPOSITES DRIVEN BY Cd INTERCALATION IN GaSe LAMELLAR CRYSTALS
(2015) Caraman, Iuliana; Kantser, Valeriu; Evtodiev, Igor; Leontie, Liviu; Arzumanyan, Grigory; Untila, Dumitru; Dmitroglo, Liliana
A new composite material composed of GaSe and CdSe has been obtained by treatment of GaSe single-crystal lamellas in Cd vapors at temperatures of 773853 K and intercalation of Cd interlayers. The structure and optical properties of the GaSe-CdSe composite material have been studied. The content of CdSe crystallites was found to grow with increasing treatment temperature or with increasing duration of treatment at a constant temperature. Analysis of XRD, PL, XPS, AFM, and Raman patterns has shown that the heterogeneous composite composed of micro and nanocrystallites of CdSe in GaSe can be obtained by Cd intercalation in a temperature range of 753853 K. On the basis of Raman spectrum, the vibrational modes of the composite have been identified. The PL of these materials contains emission bands of free and bound excitons, donor-acceptor bands, and bands of recombination via impurity levels. The PL emission spectra measured at a temperature of 78 and 300 K for the composites result from the overlapping of the emission bands of the components of GaSe doped with Cd and the CdSe crystallites.