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Article Citation - WoS: 5Citation - Scopus: 5Acoustic Phonons Scattering Mobility and Carrier Effective Mass in In6s7< Crystals(Elsevier Science Sa, 2006) Qasrawi, A. F.; Gasanly, N. M.Systematic dark electrical resistivity and Hall coefficient measurements have been carried out in the temperature range of 170-320 K on n-type In6S7 crystals. The analysis of the electrical resistivity and carrier concentration reveals the intrinsic type of conduction with an average energy band gap of similar to 0.75 eV The carrier effective masses of the conduction and valence bands were calculated from the intrinsic temperature-dependent carrier concentration data and were found to be 0.565m(0) and 2.020m(0), respectively. The temperature-dependent Hall mobility was observed to follow the mu alpha T-3/2 law and was analyzed assuming the domination of acoustic phonons scattering. The acoustic phonons scattering mobility was calculated from the crystal's structural data with no assumptions. The experimental Hall mobility data of In6S7 crystals coincides with the theoretical acoustic phonons scattering mobility data with acoustic deformation potential of 6.4 eV. (c) 2006 Elsevier B.V. All rights reserved.Article Citation - WoS: 10Citation - Scopus: 11Dispersive Optical Constants of Thermally Deposited Agin5s8< Thin Films(Elsevier Science Sa, 2008) Qasrawi, A. F.Agln(5)S(8) thin films were obtained by the thermal evaporation of Agln(5)S(8) crystals onto ultrasonically cleaned glass substrates. The films are found to exhibit polycrystalline cubic structure. The calculated lattice parameter of the unit cell (a) is 10.78 angstrom. The transmittance data of the as grown films which was recorded at 300 K in the incidence wavelength (lambda) range of 320-1000 nm are used to calculate the refractive, n(lambda). The transmittance and reflectance data are also used to calculate the absorption coefficient of the as grown Agln5S8 thin films. The fundamental absorption edge is found to be corresponding to a direct allowed transitions energy band gap. This band-to-band transition energy is found to be 1.78 eV and it is consistent with that reported for Agln(5)S(8) single crystals. (c) 2007 Elsevier B.V. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 1Hydrogen Implantation Effects on the Electrical and Optical Properties of Inse Thin Films(Tubitak Scientific & Technological Research Council Turkey, 2012) Qasrawi, Atef Fayez; Ilaiwi, Khaled Faysal; Polimeni, AntonioThe effects of hydrogen ion implantation on the structural, electrical and optical properties of amorphous InSe thin films have been investigated. X-ray diffraction analysis revealed no change in the structure of the films. An implantation of 7.3 x 10(18) ions/cm(2) decreased the electrical conductivity by three orders of magnitude at 300 K. Similarly, the conductivity activation energy, which was calculated in the temperature range of 300-420 K, decreased from 210 to 78 meV by H-ion implantation. The optical measurements showed that the direct allowed transitions energy band gap of amorphous InSe films has decreased from 1.50 to 0.97 eV by implantation. Furthermore, significant decreases in the dispersion and oscillator energy, static refractive index and static dielectric constants are also observed by hydrogen implantation.Article Citation - WoS: 17Citation - Scopus: 17Trap Distribution in Tlins2 Layered Crystals From Thermally Stimulated Current Measurements(Korean Physical Soc, 2008) Isik, M.; Goksen, K.; Gasanly, N. M.; Ozkan, H.We have carried out thermally stimulated current (TSC) measurements with the current flowing along the layer on as-grown TlInS2 layered single crystals in the low temperature range 10 - 110 K with different heating rates of 0.1 - 1.5 K/s. Experimental evidence was found for the presence of two shallow electron trapping centers with activation energies of 12 and 14 meV. Their capture cross sections have been determined as 2.2 x 10(-23) and 7.1 x 10(-25) cm(2), respectively. It was concluded that retrapping in these centers is negligible, which was confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumed slow retrapping. An exponential distribution of electron traps was revealed from the analysis of the TSC data obtained at different light excitation temperatures. This experimental technique provided a value of 27 meV/decade for the trap distribution. The parameters of the monoclinic unit cell were determined by studying the X-ray powder diffraction.Article Citation - WoS: 2Citation - Scopus: 2Thermoluminescence Characteristics of Tl4gain3< Layered Single Crystals(Taylor & Francis Ltd, 2014) Delice, S.; Isik, M.; Gasanly, N. M.The properties of trapping centres in - as grown - Tl4GaIn3S8 layered single crystals were investigated in the temperature range of 10-300K using thermoluminescence (TL) measurements. TL curve was analysed to characterize the defects responsible for the observed peaks. Thermal activation energies of the trapping centres were determined using various methods: curve fitting, initial rise and peak shape methods. The results indicated that the peak observed in the low-temperature region composed of many overlapped peaks corresponding to distributed trapping centres in the crystal structure. The apparent thermal energies of the distributed traps were observed to be shifted from similar to 12 to similar to 125meV by increasing the illumination temperature from 10 to 36K. The analysis revealed that the first-order kinetics (slow retrapping) obeys for deeper level located at 292meV.Article Citation - WoS: 5Citation - Scopus: 6Photoelectronic and Electrical Properties of Tl2ingas4< Layered Crystals(Pergamon-elsevier Science Ltd, 2007) Qasrawi, A. F.; Gasanly, N. M.Tl2InGaS4 layered crystals are studied through the dark electrical conductivity, space charge limited current and illumination- and temperature-dependent photoconductivity measurements in the temperature regions of 220-350 K, 300-400 K and 200-350 K, respectively. The space charge limited current measurements revealed the existence of a single discrete trapping level located at 0.44 eV. The dark electrical conductivity showed the existence of two energy levels of 0.32 eV and 0.60 eV being dominant above and below 300 K, respectively. The photoconductivity measurements reflected the existence of two other energy levels located at 0.28 eV and 0.19 eV at high and low temperatures, respectively. The photocurrent is observed to increase with increasing temperature up to a maximum temperature of 330 K. The illumination dependence of photoconductivity is found to exhibit supralinear recombination in all the studied temperature ranges. The change in recombination mechanism is attributed to exchange in the behavior of sensitizing and recombination centers. (C) 2006 Elsevier Ltd. All rights reserved.Article Defect Characterization of Ga4se3< Layered Single Crystals by Thermoluminescence(indian Acad Sciences, 2016) Isik, M.; Delice, S.; Gasanly, N.Trapping centres in undoped Ga4Se3S single crystals grown by Bridgman method were characterized for the first time by thermoluminescence (TL) measurements carried out in the low-temperature range of 15-300 K. After illuminating the sample with blue light (similar to 470 nm) at 15 K, TL glow curve exhibited one peak around 74 K when measured with a heating rate of 0.4 K/s. The results of the various analysis methods were in good agreement about the presence of one trapping centre with an activation energy of 27 meV. Analysis of curve fitting method indicated that mixed order of kinetics dominates the trapping process. Heating rate dependence and distribution of the traps associated with the observed TL peak were also studied. The shift of peak maximum temperature from 74 to 113 K with increasing rate from 0.4 to 1.2 K/s was revealed. Distribution of traps was investigated using an experimental technique based on cleaning the centres giving emission at lower temperatures. Activation energies of the levels were observed to be increasing from 27 to 40 meV by rising the stopping temperature from 15 to 36 K.Article Citation - WoS: 28Citation - Scopus: 10Electrical Conductivity and Hall Mobility in P-Type Tlgase2 Crystals(Pergamon-elsevier Science Ltd, 2004) Qasrawi, AF; Qasrawı, Atef Fayez Hasan; Gasanly, NM; Qasrawı, Atef Fayez Hasan; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics EngineeringSystematic dark electrical conductivity and Hall mobility measurements have been carried out in the temperature range of 200-350 K on p-type TlGaSe2 crystals. The analysis of the temperature-dependent electrical conductivity and carrier concentration reveals the extrinsic type of conduction with an acceptor impurity level located at 0.33 eV, and donor and acceptor concentrations of 9.0 x 10(15) and 1.3 x 10(16) cm(-3), respectively. A hole and electron effective masses of 0.520m(0) and 0.325m(0), respectively, with a donor to acceptor compensating ratio of 0.69 are also being identified. The Hall mobility is found to be limited by the hole-phonon short-range interactions scattering with a hole-phonon coupling constant of 0.17. (C) 2004 Elsevier Ltd. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 4Crystal Data and Indirect Optical Transitions in Tl2ingase4< Crystals(Pergamon-elsevier Science Ltd, 2008) Qasrawi, A. F.; Gasanly, N. M.The room temperature crystal data and the optical properties of the Bridgman method grown Tl2InGaSe4 crystals are reported and discussed. The X-ray diffraction technique has revealed that Tl2InGaSe4 is a single phase crystal of monoclinic structure. The unit cell lattice parameters, which were recalculated from the X-ray data, are found to be a = 0.77244 nm, b = 0.64945 nm, c = 0.92205 nm and beta = 95.03 degrees. The temperature dependence of the optical band gap of Tl2InGaSe4 single crystal in the temperature region of 290-500 K has also been investigated. The absorption coefficient was calculated from the transmittance and reflectance data in the incident photon energy range of 1.60-2.10 eV. The absorption edge is observed to shift toward lower energy values as temperature increases. The fundamental absorption edge corresponds to indirect allowed transition energy gap of 1.86 eV that exhibited a temperature coefficient gamma = -3.53 x 10(-4) eV/K. (C) 2007 Elsevier Ltd. All rights reserved.Article Citation - WoS: 32Citation - Scopus: 32Temperature Dependence of the Band Gap, Refractive Index and Single-Oscillator Parameters of Amorphous Indium Selenide Thin Films(Elsevier Science Bv, 2007) Qasrawi, A. F.InSe thin films are obtained by evaporating InSe crystal onto ultrasonically cleaned glass substrates under pressure of similar to 10(-5) Torr. The structural and compositional analysis revealed that these films are of amorphous nature and are atomically composed of similar to 51% In and similar to 49% Se. The reflectance and transmittance of the films are measured at various temperatures (300-450 K) in the incident photon energy range of 1.1-2.1 eV. The direct allowed transitions band gap - calculated at various temperatures - show a linear dependence on temperature. The absolute zero value band gap and the rate of change of the band gap with temperature are found to be (1.62 +/- 0.01) eV and -(4.27 +/- 0.02) x 10(-4) eV/K, respectively. The room temperature refractive index is estimated from the transmittance spectrum. The later analysis allowed the identification of the static refractive index, static dielectric constant, oscillator strength and oscillator energy. (c) 2006 Elsevier B.V. All rights reserved.
