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Subject: search.filters.subject.semiconductor heterojunction

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    Nanolamellar structures of Oxide-AIIIBVI: Cd semiconductors type for use as detectors of radiation in the UV spectral region [Articol]
    (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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    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.