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Article Citation - WoS: 2Citation - Scopus: 1Investigation of Conductivity Characteristics of Zn-In Thin Films(World Scientific Publ Co Pte Ltd, 2020) Gullu, H. H.; Parlak, M.Zn-In-Se thin films were fabricated on the ultrasonically cleaned glass substrates masked with clover-shaped geometry by thermal evaporation of its elemental sources. Temperature-dependent conductivity characteristics of the films were investigated under dark and illuminated conditions. The semiconductor type of the films was found as n-type by thermal probe test. According to the van der Pauw technique, the dark electrical conductivity analyses showed that the variations of conductivity of unannealed and annealed at 300 degrees C samples are in exponential dependence of temperature. These conductivity profiles were found to be dominated by the thermionic emission at high temperature region whereas their behaviors at low temperatures were modeled by hopping theory. On the contrary, as a result of the further annealing temperatures, the surface of the samples showed semi-metallic characteristics with deviating from expected Arrhenius behavior. In addition, the temperature-dependent photoconductivity of the films was analyzed under different illumination intensities and the results were explained by the supra-linear characteristic based on the two-center recombination model.Article Citation - WoS: 29Citation - Scopus: 28Optoelectronical Properties of Polycrystalline Β-Gase Thin Films(Wiley-v C H verlag Gmbh, 2006) Qasrawi, AF; Ahmad, MMSPolycrystalline beta-GaSe thin films were obtained by the thermal evaporation of GaSe crystals onto glass substrates kept at 300 degrees C under a pressure of 10(-5) Torr. The transmittance and reflectance of these films was measured in the incident photon energy range of 1.1-3.70 eV. The absorption coefficient spectral analysis in the sharp absorption region revealed a direct allowed transitions band gap of 1.83 eV. The data analysis allowed the identification of the dispersive optical parameters by calculating the refractive index in the wavelength region of 620-1100 nm. In addition, the photocurrent of the samples was studied as function of incident illumination-intensity and temperature. The photocurrent is found to exhibit sublinear and supralinear character above and below 270 K, respectively. The temperature dependent photocurrent data analysis allowed the calculation of photocurrent activation energies as 603, 119 and 45 meV being dominant in the temperature regions of 250-300 K, 180-240 K and 80-160 K, respectively. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Article Citation - WoS: 1Citation - Scopus: 1Optoelectronic Properties of Tl3inse4 Single Crystals(Taylor & Francis Ltd, 2010) Qasrawi, A. F.; Gasanly, N. M.The crystal structure, temperature-dependent electrical conductivity, Hall coefficient, current-voltage characteristics, absorption spectra and temperature- and illumination-dependent photoconductivity of Tl3InSe4 single crystals were investigated. Tl3InSe4 crystallises in a body-centred lattice with tetragonal symmetry and belongs to the space group [image omitted]. The crystals are extrinsic p-type semiconductors and exhibit a conductivity conversion from p- to n-type at a critical temperature, Tc, of 283 K. They are observed to have Schottky diode properties in an Ag/Tl3InSe4/Ag Schottky barrier device structure. The absorption spectra displays two maxima, one related to an indirect energy band gap of 1.20 eV and another corresponding to exciton transitions. The photocurrent is observed to be strongly affected by the conductivity type of the crystal. The incident light intensity dependence of the photocurrent is found to be supralinear, linear and sublinear, indicating strong recombination at the surface, monomolecular recombination and bimolecular recombination, respectively, in the regions where the sample is p-type ([image omitted]), at [image omitted], and in the n-type region ([image omitted]). In the n-type region, the photocurrent increases with decreasing temperature down to 250 K, below which the photocurrent is temperature invariant. The change in recombination mechanism is attributed to the change in the behaviour of sensitising and recombination centres.
