Browsing by Author "Rotaru, Irina"

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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.
INSTRUMENTE INTERACTIVE DE MĂSURĂ PENTRU ÎNVĂŢĂMÂNTUL MODERN
(CEP USM, 2014) Luchian, Efimia; Evtodiev, Silvia; Rotaru, Irina; Untila, Dumitru
MORFOLOGIA SUPRAFEŢEI ŞI PROPRIETĂŢILE OPTICE ŞI FOTOELECTRICE ALE HETEROJONCŢIUNILOR CDTE-GATE
(CEP USM, 2014) Spalatu, Nicolae; Evtodiev, Igor; Caraman, Iuliana; Leontie, Liviu; Rotaru, Irina; Until, Dumitru; Caraman, Mihail
OPTICAL PROPERTIES OF GaTe-ZnTe NANOLAMELLAE COMPOSITE
(2015) Spalatu, Nicolae; Evtodiev, Igor; Caraman, Iuliana; Evtodiev, Silvia; Rotaru, Irina; Caraman, Mihail; Untilă, Dumitru
A material composed of GaTe and ZnTe crystallites with average diameter of ~ 37 nm and 68 nm respectively was obtained by heat treatment at the temperature of 1000K and 1073K of GaTe plates in Zn vapour for 24 hours. The absorbance spectra of composite material obtained at 1073K and that calculated from diffuse reflection using the Kubelka-Munk formula contains the bands characteristic for light absorption in ZnTe and GaTe crystallites. The photoluminescence spectrum of composite material at the temperature of 80K is composed to the excitonic band in GaTe and impurity bands of ZnTe crystallites.
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.
STUDIUL STRUCTURII ŞI MECANISME DE GENERARE-RECOMBINARE ÎN COMPOZITE NANOLAMELARE OBŢINUTE PRIN INTERCALAREA CU CD A MONOCRISTALELOR GASE ŞI GASE:EU
(CEP USM, 2014) Untila, Dumitru; Dmitrolo, Liliana; Evtodiev, Igor; Caraman, Iuliana; Luchian, Efimia; Rotaru, Irina; Gorobcic, Tatiana