2. Articole
Permanent URI for this collectionhttps://msuir.usm.md/handle/123456789/47
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Item ELECTRICAL PROPERTIES OF THERMALLY ANNEALED CdS THIN FILMS OBTAINED BY CHEMICAL BATH DEPOSITION(Institute of Electrical and Electronics Engineers Inc., 2011-10-17) Scorțescu, Dumitru; Maticiuc, Natalia; Nicorici, Valentina; Spalatu, Nicolae; Potlog, Tamara; Hiie, Jaan; Valdna, VelloElectrical conductivity and the Hall-effect are investigated in the temperature interval (80-400) K on thermally annealed in H 2 CdS thin films obtained by chemical bath deposition. Different characters of the temperature dependence of conductibility are observed in the CdS films annealed at different temperatures. The Hall measurements allow calculating the values of the NA , N D , n ex and ED . According to Hall measurements the CdS films show several donor levels at different energetic depths in dependence of the annealing temperature. The sample annealed at high temperatures than 350oC proves to be compensated with a sharply decreasing electrical conductivity with the temperature decrease.Item ELECTRICAL PROPERTIES OF THERMAL ANNEALED IN VACUUM SPRAY DEPOSITED AL-DOPED ZnO THIN FILMS(Springer Nature, 2020) Potlog, Tamara; Lungu, Ion; Raevschi, Simion; Botnariuc, Vasile; Robu, Stephan; Worasawat, Suchada; Mimura, HidenoriAl-doped ZnO thin films have been prepared by spray pyrolysis, which facilitates the incorporation of a higher percentage of dopant atoms. The vacuum thermally annealed at 420 °C temperature thin films have been characterized by X-ray diffraction (XRD), optical spectroscopy. Electrical conductivity and the Hall effect are investigated in the temperature interval (77–300) K. X-ray analysis results reveal that all the films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction (002) plane. Different characters of the temperature dependence of conductibility are observed in the Al-doped ZnO films vacuum thermally annealed at 420 °C temperature. In all cases, the conductivity, mobility carriers and carriers’ concentration of ZnO thin films obtained under Ar are higher than under O2 atmosphere, unless they are not doped. of your paper no longer than 300 words.Item PURIFICATION OF ZNSE CRYSTALS FROM ELECTRICALLY ACTIVE BACKGROUND IMPURITIES BY YTTERBIUM DOPING(John Wiley & Sons, 2014) Radevici, Ivan; Sushkevich, Konstantin; Sirkeli, Vadim; Nedeoglo, Dmitrii; Nedeoglo, Natalia; Huhtinen, Hannu; Paturi, PetriinaHall coefficient, electrical conductivity, and electron mobility are investigated for n-ZnSe:Yb single crystals with high concentration of electrically active background impuritiesItem In2O3-BASED THERMOELECTRIC MATERIALS: THE STATE OF THE ART AND THE ROLE OF SURFACE STATE IN THE IMPROVEMENT OF THE EFFICIENCY OF THERMOELECTRIC CONVERSION(MDPI, 2018) Korotcenkov, Ghenadii; Brinzari, Vladimir; Ham, Moon-HoIn this paper, the thermoelectric properties of In2 O3 -based materials in comparison with other thermoelectric materials are considered. It is shown that nanostructured In2 O3 Sn-based oxides are promising for thermoelectric applications at moderate temperatures. Due to the nanostructure, specific surface properties of In2 O3 and filtering effects, it is possible to significantly reduce the thermal conductivity and achieve an efficiency of thermoelectric conversion inaccessible to bulk materials. It is also shown that a specific surface state at the intergrain boundary, optimal for maximizing the filtering effect, can be achieved through (1) the engineering of grain boundary parameters, (2) controlling the composition of the surrounding atmosphere, and (3) selecting the appropriate operating temperature.Item Optical Properties of III–VI Lamellar Semiconductors Doped with Cu and Cd and of Related III–VI/Native Oxide Structures(American Scientific Publishers, 2011) Evtodiev, Silvia; Caraman, Iulia; Dmitroglo, Liliana; Leontie, L.; Nedeff, V.; Dafinei, A.; Lazar, G.; Evtodiev, I.GaS, GaSe and GaTe are typical representatives of III–VI layered semiconductor materials, showing highly anisotropic mechanical and optical properties. At photon energies hν < E g , the anisotropy ratio for the absorption coefficients at the n = 1 excitonic peak, corresponding to E →‖C → and E →⊥C → polarizations, is α ‖/α ⊥≈15. Optical functions n e (λ) and n o (λ) of GaS and GaSe in the wavelength range 0.36–22 μm have been determined. For the photon energies hν < E g ind, these correspond to a normal dispersion and can be described by power-law wavelength dependences. By means of FTIR transmission and reflection spectroscopy in the spectral range of 1000–85 cm−1, for plan-parallel plates with thickness between several tens of nanometers and centimeters, the wavenumbers of longitudinal optical ν(LO) and transverse optical ν(TO) phonons have been determined for GaSe [ν ⊥(LO) = 254 cm−1, ν ⊥(TO) = 214 cm−1], GaS [ν ⊥(LO) = 359 cm−1, ν ⊥(TO) = 297 cm−1, ν ‖(LO) = 336 cm−1], and GaTe [ν(LO) = 164 cm−1, ν(TO) = 118 cm−1].Item CERCETAREA CAPACITĂȚII ȘI CONDUCTIBILITĂȚII ELECTRICE ALE JONCȚIUNILOR DIN P-INP(CEP USM, 2017) Botnariuc, Vasile; Gagara, Ludmila; Gorceac, Leonid; Cinic, Boris; Covali, Andrei; Raevschi, Simion; Rotaru, CornelAu fost studiate caracteristicile capacitate-tensiune-conductabilitate-frecvenţă ale homojoncţiunilor n+-p-p+InP cu şi fără strat frontal n+CdS obţinute cu aplicarea tehnologiilor din faza gazoasă în sistemul In-PCl3-H2 şi în volum cvasiînchis. S-a stabilit că distribuirea impurităţilor în regiunea sarcinii de baraj în astfel de joncţiuni este cu gradient liniar, iar la frecvenţele de 7…10 MHz impendanţa structurii este determinată de rezistenţa inductivă. Concentraţia stărilor superficiale pentru structurile n+-p-p+InP cu strat frontal de n+CdS este cu un ordin mai mică decât fără acest strat, ceea ceva spori eficienţa CF obţinute în baza lor.