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Citation - WoS: 16
Citation - Scopus: 17
Investigation of Localized Levels in Gas_0.5se_{0.5< Layered Crystals by Means of Electrical, Space-Charge Limited Current and Photoconductivity Measurements}
(Wiley-v C H verlag Gmbh, 2002) Qasrawi, AF; Gasanly, NM
To 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.
Citation - WoS: 13
Citation - Scopus: 13
Light Illumination Effect on the Electrical and Photovoltaic Properties of In₆s_{7< Crystals}
(Iop Publishing Ltd, 2006) Qasrawi, AF; Gasanly, NM
The 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.
Citation - WoS: 26
Citation - Scopus: 26
Etectron-Phonon Short-Range Interactions Mobility and P- To N-Type Conversion in Tlgas₂ Crystal
(Wiley-v C H verlag Gmbh, 2006) Qasrawi, AF; Gasanly, NM
The conductivity type conversion from p- to n-type at a critical temperature of 315 K in TlGaS2 crystals is observed through the Hall effect measurements in the temperature range of 200-350 K. The analysis of the temperature-dependent electrical resistivity, Hall coefficient and carrier concentration data reveals the extrinsic type of conduction with donor impurity levels that behave as acceptor levels when are empty. The data analysis allowed the calculation of hole and electron effective masses of 0.36m(0) and 0.23m(0), respectively. In addition, the temperature-dependent Hall mobility is found to decrease with temperature following a logarithmic slope of similar to 1.6. The Hall mobility in the n-region is limited by the electron-phonon short-range interactions scattering with an electron-phonon coupling constant of 0.21. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Citation - WoS: 26
Citation - Scopus: 26
Photoelectronic, optical and electrical properties of TlInS₂ single crystals
(Wiley-v C H verlag Gmbh, 2003) Qasrawi, AF; Gasanly, NM
To specify the donor energy levels in TlInS2 single crystals, the dark electrical resistivity, photoconductivity and Hall measurements were carried out in the temperature range of 100-400 K, 110-350 K and 170-400 K, respectively. The Hall measurements revealed that the crystals exhibit an anomalous behavior of Hall voltage by changing sign (from p-type to n-type conductivity) at 315 K. By means of the temperature dependence of dark electrical resistivity, Hall coefficient and photocurrent measurements the donor energy levels located at 360, 280, 152 and 112 meV were detected. The photocurrent-illumination intensity dependence follows the law I-Ph proportional to F-gamma with gamma being 1.0 (linear), 0.5 (sublinear), 1.0 (linear) and 1.3 (supralinear) at low, moderate, high and very high illumination intensities indicating the monomolecular in the bulk, bimolecular and strong recombination at the surface, respectively. The photocurrent is observed to increase with increasing temperature up to a maximum temperature (T-m) 245 K. T is observed to shift to higher temperature as F increases, and disappears in the region where I-Ph-F dependence is supralinear. The phenomenon is attributed to the exchange in the behavior of the sensitizing and recombination centers. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA. Weinheim.
Citation - WoS: 28
Citation - Scopus: 27
Photoelectronic and Electrical Properties of Cuin₅s_{8< Single Crystals}
(Wiley-v C H verlag Gmbh, 2003) Qasrawi, AF; Gasanly, NM
To identify the impurity levels in CuIn5S8 single crystals, the dark electrical conductivity and photoconductivity measurements were carried out in the temperature range of 50-460 K. The data reflect the intrinsic and extrinsic nature of the crystals above and below 300 K, respectively. Energy band gaps of 1.35 and 1.31 eV at 0 K and 300 K, were defined from the dark conductivity measurements and the photocurrent spectra, respectively. The dark and photoconductivity data in the extrinsic temperature region reflect the existence of two independent donor energy levels located at 130 and 16 meV. The photocurrent-illumination intensity dependence (F) follows the law I(ph)alphaF(gamma), with gamma being 1.0, 0.5 and 1.0 at low, moderate and high intensities indicating the domination of monomolecular, bimolecular and strong recombination at the surface, respectively. In the intrinsic region and in the temperature region where the shallow donor energy level 16 meV is dominant, the free electron life time, tau(n), is found to be constant with increasing F. In the temperature region 140 K < T < 210 K, the free electron life time increases with increasing illumination intensity showing the supralinear character. Below 140 K, tau(n) decrease with decreasing illumination intensity. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Citation - WoS: 27
Citation - Scopus: 30
Crystal Data, Electrical Resistivity, and Hall Mobility of N-Type Agin₅s_{8< Single Crystals}
(Wiley-v C H verlag Gmbh, 2001) Qasrawi, AF; Gasanly, NM
The 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.
Citation - WoS: 25
Citation - Scopus: 25
Temperature Effect on Dark Electrical Conductivity, Hall Coefficient, Space Charge Limited Current and Photoconductivity of Tlgas₂ Single Crystals
(Iop Publishing Ltd, 2005) Qasrawi, AF; Gasanly, NM
The 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.
Citation - WoS: 28
Citation - Scopus: 10
Electrical 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 Engineering
Systematic 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.
Citation - WoS: 1
Carrier Transport Properties of Ins Single Crystals
(Wiley-blackwell, 2003) Qasrawi, AF; Gasanly, NM
The electrical resistivity and Hall effect of indium sulfide single crystals are measured in the temperature range from 25 to 350 K. The donor energy levels located at 500, 40 and 10 meV below the conduction band are identified from both measurements. The data analysis of the temperature-dependent Hall effect measurements revealed a carrier effective mass of 0.95 m(0), a carrier compensation ratio of 0.9 and an acoustic deformation potential of 6 eV. The Hall mobility data are analyzed assuming the carrier scattering by acoustic and polar optical phonons, and ionized impurities.
Citation - WoS: 30
Citation - Scopus: 30
Optoelectronic and Electrical Properties of Tlgas₂ Single Crystal
(Wiley-v C H verlag Gmbh, 2005) Qasrawi, AF; Gasanly, NM
The optoelectronic and electrical properties of TIGaS2 single crystals have been investigated by means of room temperature transmittance and reflectance spectral analysis, Hall coefficient, dark electrical resistivity and photocurrent measurements in the temperature range of 200-350 K. The optical data have revealed an indirect and direct allowed transition band gaps of 2.45 and 2.51 eV, an oscillator and dispersion energy of 5.04 and 26.45 eV, respectively, a static dielectric constant of 6.25 and static refractive index of 2.50. The dark Hall coefficient measurements have shown that the crystals exhibit a conductivity type conversion from p-type to n-type at a critical temperature of 315 K. Deep donor and acceptor energy levels of 0.37/0.36 eV and 0.66 eV has been calculated from the temperature dependence of Hall coefficient and resistivity, and photocurrent measurements, respectively. The photocurrent decreases with decreasing temperature. The analysis of the photocurrent data have revealed that, the recombination mechanism is linear and supralinear above and below 290 K, respectively. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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