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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: 2Citation - Scopus: 3Crystal Data and Some Physical Properties of Tl2ingate4< Crystals(Wiley-v C H verlag Gmbh, 2007) Qasrawi, A. F.; Gasanly, N. M.The room temperature crystal data, Debye temperature, dark and photoelectrical properties of the Bridgman method grown Tl2InGaTe4 crystals are reported for the first time. The X-ray diffraction technique has revealed that Tl(2)lnGaTe(4) is a single phase crystal of tetragonal body-centered structure belonging to the D-4H(18) - I4mcm space group. A Debye temperature of 124 K is calculated from the results of the X-ray data. The current-voltage measurements have shown the existence of the switching property of the crystals at a critical voltage of 80 V. The dark electrical resistivity and Hall effect measurements indicated the n-type conduction with an electrical resistivity, electron density and Hall mobility of 2.49x 10(3) Omega cm, 4.76x 10(12) cm(-3) and 527 cm V-2(-1) s(-1), respectively. The photosensitivity measurements on the crystal revealed that, the variation of photocurrent with illumination intensity is linear, indicating the domination of monomolecular recombination at room temperature. Moreover, the spectral distribution of the photocurrent allowed the determination of the energy band gap of the crystal studied as 0.88 cV.
