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Article Carrier Scattering Mechanisms in GaS0.5Se0.5 Layered Crystals(Wiley-VCH Verlag GmbH, 2002) Qasrawi, AF; Gasanly, NMSystematic dark electrical resistivity and Hall mobility measurements have been carried out in the temperature range 150-400 K on n-type GaS0.5Se0.5 layered crystals. The analysis of temperature dependent electrical resistivity and carrier concentration reveals the extrinsic type of conduction with a donor impurity level located at 0.44 eV, donor and acceptor concentrations of 3.4x10(17) and 4.1x10(17) cm(-1), respectively, and an electron effective mass of 0.41 m(o). The Hall mobility is limited by the electron-phonon short-range interactions scattering at high temperatures combined with the ionized impurity scattering at low temperatures. The electron-phonon short-range interactions scattering mobility analysis reveals an electron-phonon coupling constant of 0.25 and conduction band deformation potential of 5.57 eV/Angstrom.Article Crystal Data, Electrical Resistivity, and Hall Mobility of n-Type AgIn5S8 Single Crystals(Wiley-VCH Verlag GmbH, 2001) Qasrawi, AF; Gasanly, NMThe X-ray diffraction has revealed that AgIn5S8 is a single phase crystal of cubic spinel structure. The value of the unit cell parameter for this crystal is 1.08286 nm. The electrical resistivity and Hall effect of n-type AgIn5S8 crystals are measured in the temperature range of 50-400 K. A carrier effective mass of 0.20 m(0), an acceptor to donor concentration ratio of 0.8 and an acoustic phonons deformation potential of 20 eV are identified from the Hall effect measurement. The Hall mobility data art: analyzed assuming the carrier scattering by acoustic and polar optical phonons, and ionized impurities.Article Effect of Magnetic Field and γ Irradiation on the Properties of Tl-2212 Superconducting Tape(Wiley-VCH Verlag GmbH, 2002) Ercan, I; Kayed, TSThe critical temperature and critical current of Tl-2212 superconducting sample in the form of a tape have been studied near T-c under magnetic field and gamma irradiation. T-c decreases from 109 to 94 K with increase of magnetic field up to 300 mT. In 77-109 K range, J(c) decreases rapidly in low fields up to around 50 mT followed by a very slow decrease in J(c) up to 300 mT. T-c of the sample did not change up to 100 MR gamma dose and then started to decrease from 109 to 102 K with increase of gamma dose up to 800 MR, most of the change taking place in high doses. The critical currents of the sample decreased steadily with gamma irradiation up to 600 MR after which no further change was noticed.Article Citation - Scopus: 11Cd-Doping Effects on the Properties of Polycrystalline Α-In2se3 Thin Films(Wiley-VCH Verlag GmbH, 2002) Qasrawi,A.F.The X-ray diffraction has revealed that the polycrystalline hexagonal structured α-In2Se3 thin films grown at substrate temperature of 200°C with the unit cell parameters a=4.03°A and c=19.23°A becomes polycrystalline hexagonal structured InSe with a unit cell parameters of a=4.00°A and c=16.63°A by Cd-doping. The analysis of the conductivity temperature dependence in the range 300-40 K revealed that the thermionic emission of charged carriers and the variable range hopping are the predominant conduction mechanism above and below 100 K, respectively. Hall measurements revealed that the mobility is limited by the scattering of charged carriers through the grain boundaries above 200 K and 120 K for the undoped and Cd-doped samples, respectively. The photocurrent (Iph) increases with increasing illumination intensity (F) and decreasing temperature up to a maximum temperature of ∼100 K, below which Iph is temperature invariant. It is found to have the monomolecular and bimolecular recombination characters at low and high illumination intensities, respectively. The Cd-doping increases the density of trapping states that changes the position of the dark Fermi level leading to the deviation from linearity in the dependence of Iph on F at low illumination intensities.Article Investigation of Localized Levels in GaS0.5Se0.5 Layered Crystals by Means of Electrical, Space-Charge Limited Current and Photoconductivity Measurements(Wiley-VCH Verlag GmbH, 2002) Qasrawi, AF; Gasanly, NMTo identify the localized levels in GaS0.5Se0.5 single crystals, the dark electrical conductivity, current-voltage characteristics and photoconductivity measurements were carried out in the temperature range of 250-400 K. Temperature dependence of dark electrical conductivity and the space-charge limited current studies indicate the presence of a single discrete trapping level located at 0.31 eV below the conduction band with a density of about 1.3 x 10(15) cm(-3). The conductivity data above 320 K reveal an additional donor level with activation energy of 0.40 eV indicating the extrinsic nature of conduction. The spectral distribution of photocurrent in the photon energy range of 0.65-5.9 eV reveals an indirect band gap of 2.26 eV. The photocurrent-illumination intensity dependence follows the law I-ph proportional to F-gamma, with gamma being 1.0, 0.65, and 0.5 at low, moderate and high illumination intensities, respectively. The corresponding behavior indicates the domination of monomolecular recombination, near equal densities of trapped and recombination centers and bimolecular recombination. It is observed that the photocurrent increases in the temperature range from 250 K up to T-m = 360 K and decreases for T > T-m. The temperature dependence of the photocurrent reveals two additional impurity levels with activation energies of 0.14 and 0.10 eV below and above Tm, respectively.Article Crystal Data, Photoconductivity and Carrier Scattering Mechanisms in CuIn5S8 Single Crystals(Wiley-VCH Verlag GmbH, 2001) Qasrawi, AF; Gasanly, NMThe X-ray diffraction has revealed that CuIn5S8 is a single phase crystal of cubic spinet structure. The value of the unit cell parameter for this crystal is 1.06736 nm. The crystal is assigned to the conventional space group Fd3m. The photocurrent is found to have the characteristic of monomolecular and bimolecular recombination at low and high illumination intensities, respectively. The electrical resistivity and Hall effect of CuIn5S8 crystals are measured in the temperature range of 50-400 K. The crystals are found to be intrinsic and extrinsic above and below 300 K, respectively. An energy band gap of similar to1.35 eV at 0 K, a carrier effective mass of 0.2 m(0), an acceptor to donor concentration ratio of 0.9, an acoustic phonon deformation potential of 10 eV and a nonpolar optical phonon deformation potential of 15 eV are identified from the resistivity and Hall measurements. The Hall mobility data are analyzed assuming the carrier scattering by polar optical phonons, acoustic combined with nonpolar optical phonons, and ionized impurities.
