Browsing by Author "Caraman, M."

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    Optical and photoelectrical characteristics of GaSe (Cu)/oxide semiconductor heterojunction [Articol]
    (2008) Evtodiev, I.; Cuculescu, E.; Arama, E.; Caraman, M.
    The AIIIBVI layered semiconductors are perspective materials for photoelectrical and luminescent device fabrication, for use in visible and near IR spectral region [1, 2]. GaSe and InSe semiconductors, having the bandgap equal to 2.0 eV and 1.2 eV respectively, are most often used for device fabrication [3, 4]. The applicability of GaSe crystals as a heterojunction component is limited by their low electrical conductivity (the hole concentration is ∼ 1013 cm-3 at 293 K) [5]. Cu (0.10 at %) doping of GaSe crystals causes the hole conductivity increase by more than 5 orders of magnitude and its value is ∼ (8÷9)⋅10-2Ω-1cm-1 [6]. Cu impurity atoms form two acceptor levels in GaSe positioned at 0.12 eV and 0.038 eV [1], which enlarge the applicability domain for these materials. The SnO2, In2O3 (SnO2), ZnO and others [7, 8] are used as optically transparent semiconductors in the visible and near IR spectral region and as an element of heterojunction based optoelectronic devices. This paper presents the investigation of the photoelectrical properties of GaSe (0.10 at % Cu)/ ZnO, In2O3, SnO2, Bi2O3, and Cu2O oxide semiconductor heterojunction.
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    Preparation and optical properties of lamellar GaSe -ZnSe nanocomposites [Articol]
    (2015) Caraman, M.; Untila, D.; Canțer, V.; Evtodiev, Igor; Caraman, Iu.; Susu, O.; Leontie, L.
    ZnSe-GaSe nanocomposite plates photoluminescent in a photon energy range of 1.80−2.64 eV were obtained via exposing GaSe single-crystal plates to a Zn-vapor heat treatment at temperatures of 673−873 K. The photoluminescence spectrum is dominated bythe self-activated emission band of ZnSe witha maximum at 2.04 eV. The average size of the ZnSe crystallites is ~45 nm. The absorption spectrum of the composite consists of two regions characteristic of direct optical transitions in GaSe crystals with a band gap of 1.99 eV and ZnSe crystallites with aband gap of 2.56 eV at room temperature.