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Article Citation - WoS: 13Citation - Scopus: 13Light Illumination Effect on the Electrical and Photovoltaic Properties of In6s7< Crystals(Iop Publishing Ltd, 2006) Qasrawi, AF; Gasanly, NMThe electrical and photoelectrical properties of In6S7 crystals have been investigated in the temperature regions of 170-300 K and 150-300 K, respectively. The dark electrical analysis revealed the intrinsic type of conduction. The energy band gap obtained from the temperature-dependent dark current is found to be 0.75 eV. It is observed that the photocurrent increases in the temperature range of 150 K up to T-m = 230 K and decreases at T > T-m. Two photoconductivity activation energies of 0.21 and 0.10 eV were determined for the temperature ranges below and above Tm, respectively. The photocurrent (I-ph)-illumination intensity (F) dependence follows the law I-ph alpha F-gamma. The value of. decreases when the temperature is raised to T-m, then it starts increasing. The change in the value. with temperature is attributed to the exchange in role between the recombination and trapping centres in the crystal. The crystals are found to exhibit photovoltaic properties. The photovoltage is recorded as a function of illumination intensity at room temperature. The maximum open-circuit voltage and short-circuit photocurrent density, which are related to an illumination intensity equivalent to one sun, are 0.12 V and 0.38 mA cm(-2), respectively.Article Citation - WoS: 8Citation - Scopus: 8Photoelectronic and Electrical Properties of Ins Crystals(Iop Publishing Ltd, 2002) Qasrawi, AF; Gasanly, NMTo identify the localized levels in InS single crystals, the dark electrical conductivity, current-voltage characteristics and photoconductivity measurements were carried out in the temperature range of 10-350 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 (10 +/- 2) meV below the conduction band with a density of about 4.8 x 10(11) cm(-3). The conductivity data above 110 K reveal an additional two independent donor levels with activation energies of (50 +/- 2) and (164 +/- 4) meV indicating the extrinsic nature of conductivity. The spectral distribution of photocurrent in the photon energy range of 0.8-3.1 eV reveals an indirect band gap of (1.91 +/- 0.04) eV. The photocurrent-illumination intensity dependence follows the law I-ph proportional to F-gamma, with gamma being 1.0 and 0.5 at low and high illumination intensities indicating the domination of monomolecular and bimolecular recombination, respectively. It is observed that the photocurrent increases in the temperature range of 10 K up to T-m = 110 K and decreases or remains constant for 110 K < T < 160 K and increases again above 160 K. The temperature dependence of the photocurrent reveals an additional shallow impurity level with activation energies of 3 meV.Article Citation - WoS: 25Citation - Scopus: 25Temperature Effect on Dark Electrical Conductivity, Hall Coefficient, Space Charge Limited Current and Photoconductivity of Tlgas2 Single Crystals(Iop Publishing Ltd, 2005) Qasrawi, AF; Gasanly, NMThe dark electrical conductivity, Hall coefficient, space charge limited current, and illumination and temperature dependences of the photocurrent of TIGaS2 single crystals in the temperature regions of 100-350, 200-350, 200-290 and 100-350 K, respectively, have been measured and analysed. The Hall coefficient measurements revealed the extrinsic type of conduction with conductivity-type conversion from p- to n-type at a critical temperature of 315 K. The temperature dependence of the dark electrical conductivity exhibits activation behaviour with activation energies (0.360 +/- 0.005) eV and (0.240 +/- 0.005) eV at high and low temperatures, respectively. The space charge limited current analysis has shown that the energy level of (0.240 +/- 0.005) eV is a trapping state with trap density of (2.2-3.9) x 10(12) cm(-3). The data analysis of the photocurrent-temperature dependence has revealed two photoconductivity activation energies of (0.660 +/- 0.005) eV and (0.360 +/- 0.005) eV in the temperature regions of 290-350 K and 220-280 K, respectively. The illumination dependence of photoconductivity is found to exhibit linear and supralinear recombination mechanisms above and below 290 K, respectively.Conference Object Citation - WoS: 9Citation - Scopus: 11Effect of Lithium Doping on the Properties of Tl-Based Superconductors(Iop Publishing Ltd, 2001) Kayed, TS; Özkan, H; Gasanly, NMThe effects of lithium doping on the formation and properties of the T1-based superconductors have been studied. Lithium atoms up to around 3 mol.% have been added to the oxides of nominal composition Tl1.8Ba2Ca2.2Cu3Ox, and the usual solid-state reaction method has been applied. Lithium additions in the range 0.23-0.29 mol.% increase the fraction of the Tl-2223 phase and significantly improve the critical temperature of the samples. Higher amounts of lithium additions diminish the Tl-2223 phase, reduce the fraction of the Tl-2212 phase, and cause separate non-superconducting phases to be formed.Article Citation - WoS: 34Citation - Scopus: 33Hall Effect, Space-Charge Limited Current and Photoconductivity Measurements on Tlgase2 Layered Crystals(Iop Publishing Ltd, 2004) Qasrawi, AF; Gasanly, NMTlGaSe2 layered crystals are studied through dark electrical conductivity, Hall mobility, space-charge limited current and illumination- and temperature-dependent photoconductivity in the temperature ranges 120-350 K, 220-350 K, 260-350 K and 120-350 K, respectively. The Hall effect measurements revealed the extrinsic p-type conduction. The Hall mobility increase with decreasing temperature is limited by the thermal lattice scattering. The space-charge limited current and dark conductivity measurements predicted the existence of a single discrete trapping level located at 330 meV with a trap concentration of (1.4-2.2) x 10(13) cm(-3). The dark electrical conductivity and photoconductivity measurements reflect the existence of three other energy levels located at 95, 46 and 26 meV at high, moderate and low temperatures, respectively. The photocurrent is observed to increase with increasing temperature up to a maximum temperature of 320 K. The illumination dependence of photoconductivity is found to exhibit sublinear, linear and supralinear recombinations at high, moderate and low temperatures, respectively. The change in recombination mechanism is attributed to the exchange in the behaviour of sensitizing and recombination centres.
