2. Articole

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

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Author: search.filters.author.Untila, DumitruSubject: search.filters.subject.GaSe

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    NANOLAMELLAR STRUCTURES OF OXIDE-AIIIBVI:Cd SEMICONDUCTORS TYPE FOR USE AS DETECTORS OF RADIATION IN THE UV SPECTRAL REGION
    (Technical University of Moldova, 2011-07-07) Dmitroglo, Liliana; Untila, Dumitru; Chetruș, Petru; Evtodiev, Igor; Caraman, Iuliana; Lazăr, Gabriel; Nedeff, Valentin
    In the paper, optical and photoelectrical properties of GaSe and InSe single crystal films of 10-5÷10-7 m submicron thickness and of semiconductor-native oxide structures obtained by annealing at (450÷700)°C in a normal atmosphere, are studied. The absorption spectrum of InSe lamella as well as of GaSe lamella in the energetic range from the red threshold up to 4,5 eV contains three bands with a rapid increase of the absorption coefficient which varies in the limits of (100÷106) cm-1 At the energies higher than 1,25 eV and 2,01 eV for InSe and GaSe respectively the light absorption are determined by the direct optical transitions in the centre of the Brillouin zone and at the energies higher than. At the absorption coefficients of (100÷102)cm-1 the indirect optic transitions are present. 3,0 eV also by the direct optical transitions in the points of the bands high symmetry. The resistive photosensitivity bands cover the spectral range Eg≤ hν ≤ 4,5 eV for lamellar photoresistors in which electric field EC6. The resistive photosensitivity band width could be controlled by the lamella thickness for d ≥1μm. The open circuit voltage spectral distribution is analysed from which results that at the oxidation temperature of 700°C in GaSe layer at the heterojunction interface the defects are formed on which the charge carriers, collected in the junction, are dissipated. The noneequilibrium charge carrier free path is of 0,8 μm.
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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.
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    FOTOLUMINESCENŢA IONILOR Eu 3+ ÎN STRUCTURI NANOLAMELARE DE GaSe INTERCALAT CU Cd
    (Universitatea de Stat „Alecu Russo“ din Bălţi, 2015) Untila, Dumitru
    În prezenta lucrare s-a studiat structura cristalină şi fotoluminescenţa (PL) la emperatura 78K a compozitului obţinut prin intercalarea lamelor monocristaline de GaSe:Eu, cu Cd din fază de vapori, la temperaturi de 753K. Compozitul studiat este alcătuit din monocristalite de CdSe şi GaSe microstructurat, şi centre de Eu3+. Spectrul de PL al lamelor monocristaline de GaSe dopat cu Eu este compus din benzile de emisie a ionului în GaSe (tranziţiile 5D0→7F0,2,4, 5D1→7F2, 5D2→7F6), banda de emisie a excitonilor indirecţi în cristalitele GaSe şi banda de emisie a cristalitelor de CdSe din compozit.