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Article Citation - WoS: 5Citation - Scopus: 5Dispersive Optical Constants of Tl2ingase4< Single Crystals(Iop Publishing Ltd, 2007) Qasrawi, A. F.; Gasanly, N. M.The structural and optical properties of Bridgman method grown Tl2InGaSe4 crystals have been investigated by means of room temperature x-ray diffraction, and transmittance and reflectance spectral analysis, respectively. The x-ray diffraction technique has shown that Tl2InGaSe4 is a single phase crystal of a monoclinic unit cell that exhibits the lattice parameters of a = 0.77244 nm, b = 0.64945 nm, c = 0.92205 nm and beta = 95.03 degrees . The optical data have revealed an indirect allowed transition band gap of 1.86 eV. The room temperature refractive index, which was calculated from the reflectance and transmittance data, allowed the identification of the dispersion and oscillator energies, static dielectric constant and static refractive index as 28.51 and 3.45 eV, 9.26 and 3.04, respectively.Article Citation - WoS: 2Citation - Scopus: 2Electron-Lattice Interaction Scattering Mobility in Tl2ingase4< Single Crystals(Iop Publishing Ltd, 2008) Qasrawi, A. F.; Gasanly, N. M.In this work, the dark electrical resistivity, charge carrier density and Hall mobility of Tl(2)InGaSe(4) single crystal have been recorded and analyzed to investigate the dominant scattering mechanism in the crystal. The data analyses have shown that this crystal exhibits an extrinsic n-type conduction. The temperature-dependent dark electrical resistivity analysis reflected the existence of two energy levels as 0.396 and 0.512 eV, being dominant above and below 260 K, respectively. The temperature dependence of the carrier density was analyzed by using the single-donor-single-acceptor model. The latter analysis has shown that the above maintained 0.512 eV energy level is a donor impurity level. The compensation ratio for this crystal is determined as 0.96. The Hall mobility of Tl(2)InGaSe(4) is found to be limited by the scattering of electron-acoustic phonon interactions. The calculated theoretical acoustic phonon scattering mobility agrees with the experimental one under the condition that the acoustic deformation potential is 12.5 eV.Article Citation - WoS: 3Citation - Scopus: 3Optoelectronic Properties of Ga4se3< Single Crystals(Iop Publishing Ltd, 2008) Qasrawi, A. F.; Gasanly, N. M.; Ilaiwi, K. F.The optoelectronic properties of Bridgman method-grown Ga(4)Se(3)S single crystals have been investigated by means of room temperature electrical resistivity, temperature-dependent photosensitivity and temperature-dependent optical absorption. The photosensitivity was observed to increase with decreasing temperature, the illumination dependence of which was found to exhibit monomolecular recombination in the bulk at 300 K. The absorption coefficient, which was calculated in the incident photon energy range of 2.01-2.35 eV, increased with increasing temperature. Consistently, the absorption edge shifts to lower energy values. The fundamental absorption edge corresponds to an indirect allowed transitions energy gap (2.08 eV at 300 K) that exhibits a temperature coefficient of -95 x 10(-4) eVK(-1).Article Citation - WoS: 5Citation - Scopus: 5Growth and Temperature Tuned Band Gap Characteristics of Nabi(moo4)2< Single Crystal(Iop Publishing Ltd, 2023) Isik, M.; Guler, I; Gasanly, N. M.Structural and optical properties of double sodium-bismuth molybdate NaBi(MoO4)(2) semiconductor compound was investigated by x-ray diffraction, Raman and transmission experiments. From the x-ray diffraction experiments, the crystal that has tetragonal structure was obtained. Vibrational modes of the crystal were found from the Raman experiments. Transmission experiments were performed in the temperature range of 10-300 K. Derivative spectroscopy analysis and absorption spectrum analysis were performed to get information about the change in band gap energy of the crystal with temperature. It was observed that the band gap energies of the crystal at different temperatures obtained from these techniques are well consisted with each other. By the help of absorption spectrum which was obtained from transmission measurements performed at varying temperatures, absolute zero value of the band gap and average phonon energy as 3.03 +/- 0.02 eV and Eph = 24 +/- 0.2 meV, respectively. Moreover, based on absorption spectrum analysis the Urbach energy of the crystal was obtained as 0.10 eV.Article Citation - WoS: 8Citation - Scopus: 8Temperature- and Photo-Excitation Effects on the Electrical Properties of Tl4se3< Crystals(Iop Publishing Ltd, 2009) Qasrawi, A. F.; Gasanly, N. M.The extrinsic energy states and the recombination mechanism in the Tl4Se3S chain crystals are being investigated by means of electrical and photoelectrical measurements for the first time. The electrical resistivity is observed to decrease exponentially with increasing temperature. The analysis of this dependence revealed three impurity levels located at 280, 68 and 48 meV. The photocurrent is observed to increase as temperature decreases down to a minimum temperature T-m=200 K. Below this temperature the photocurrent decreases upon temperature lowering. Two photoconductivity activation energies of 10 and 100 meV were determined for the temperature ranges below and above T-m, respectively. The photocurrent (I-ph) versus illumination intensity (F) dependence follows the I-ph proportional to F-gamma law. The value of gamma decreases from similar to 1.0 at 300K to similar to 0.34 at 160K. The change in the value of gamma with temperature is attributed to the exchange of roles between the monomolecular recombination at the surface near room temperature and trapping centers in the crystal, which become dominant as temperature decreases.Article Citation - WoS: 2Citation - Scopus: 2Thermoluminescence Dose Response and Kinetic Parameters of Gd-Doped Zno Nanoparticles(Iop Publishing Ltd, 2024) Isik, M.; Yildirim, T.; Guner, M.; Gasanly, N. M.This study investigates the thermoluminescence (TL) properties of undoped and gadolinium (Gd)-doped zinc oxide (ZnO) nanoparticles synthesized via sol-gel method. The crystal structure of both synthesized nanoparticles was determined as hexagonal from x-ray diffraction pattern. The TL curve of undoped ZnO nanoparticles reveals two distinct peaks at 400.5 and 479.2 K, each associated with trap centers featuring activation energies of 0.84 and 1.05 eV. TL curve of the Gd:ZnO introduced three peaks associated with trap centers at 1.10, 1.18, and 1.25 eV. Notably, the absence of the 0.84 eV trap center in Gd-doped ZnO implies a modification in the defect structure. Considering the effect of Gd-doping on the band structure and potential minor errors in the analysis results, it was stated that the traps at 1.05 and 1.10 eV levels belonged to the same defect center. Dose-dependent investigations for undoped and Gd-doped ZnO nanoparticles reveal linear behaviors in the TL response, highlighting their potential for dosimetric applications. Photoluminescence spectra of both compounds exhibited emission peaks around 455 and 577 nm, which were associated with native defect centers.Article Citation - WoS: 2Citation - Scopus: 2Investigation of Defect Levels in Bi12sio20< Single Crystals by Thermally Stimulated Current Measurements(Iop Publishing Ltd, 2021) Isik, M.; Delice, S.; Gasanly, N. M.Bi12SiO20 (BSO) single crystal belongs to the sillenite semiconducting family known as defective compounds. The present paper investigates the defect centers in BSO grown by Czochralski method by means of thermally stimulated current (TSC) measurements performed in the 10-260 K range. The TSC glow curve obtained at heating rate of beta = 0.1 K s(-1) presented several peaks associated with intrinsic defect centers. The activation energies of defect centers were revealed as 0.09, 0.15, 0.18, 0.22, 0.34, 0.70 and 0.82 eV accomplishing the curve fit analyses method. The peak maximum temperatures and orders of kinetics of each deconvoluted peak were also determined as an outcome of fitting process. TSC experiments were expanded by making the measurements at various heating rates between 0.1 and 0.3 K s(-1) to get information about the heating rate dependent peak parameters.Article Citation - WoS: 4Citation - Scopus: 5Thermal lattice scattering mobility and carrier effective mass in intrinsic Tl2InGaTe4 single crystals(Iop Publishing Ltd, 2007) Qasrawi, A. F.; Gasanly, N. M.Systematic structural, dark electrical resistivity and Hall coefficient measurements have been carried out on n- type Tl2InGaTe4 single crystals. The data from x- ray powder diffraction allowed determination of the tetragonal unit cell lattice parameters. Analysis of the electrical resistivity and carrier concentration, which was recorded in the temperature range 210 - 350 K, reveals the intrinsic type of conduction with an average energy band gap of 0.85 eV. The temperature- dependent Hall mobility was observed to follow the mu alpha T-3/2 law and was analysed assuming the domination of acoustic phonons scattering. The experimental Hall mobility data for Tl2InGaTe4 crystals agrees with the theoretical acoustic phonon scattering mobility data with an acoustic deformation potential of 7.6 eV.Article Citation - WoS: 8Citation - Scopus: 8Study of the Structural and Optical Properties of Thallium Gallium Disulfide (tlgas2) Thin Films Grown Via Thermal Evaporation(Iop Publishing Ltd, 2022) Isik, M.; Karatay, A.; Ech-Chergui, A. N.; Gasanly, N. M.Thallium gallium disulfide (TlGaS2) belonging to layered structured semiconducting family has been a significant compound due to its outstanding characteristics. Its layered characteristics take attention for two-dimensional (2D) material research area and thus TlGaS2 is known as promising layered compound to develop 2D materials for optoelectronic devices. To the best of our knowledge, the present work is the first one investigating TlGaS2 thin films grown by thermal evaporation method. The current study focused into the structural, morphological, and optical characteristics of thermally evaporated TlGaS2 thin films. X-ray diffraction pattern of the films exhibited one peak around 36.10 degrees which was associated with (-422) plane of the monoclinic crystalline structure. The atomic compositional ratio of Tl:Ga:S was found to be suitable for the chemical formula of TlGaS2. Scanning electron microscopy images showed uniformly and narrowly deposited nanoparticles with sizes varying between 100 and 200 nm. Room temperature transmission measurements were recorded to obtain the bandgap energy of the evaporated thin films. Tauc analyses indicated direct band gap energy of 2.60 eV. Finally, Urbach energy was obtained as 95 meV. The results of the present paper would provide valuable insight to 2D material technology to understand the potential device applications of the TlGaS2.Article Citation - WoS: 7Citation - Scopus: 9Analysis of the Hall Effect in Tlgate2 Single Crystals(Iop Publishing Ltd, 2009) Qasrawi, A. F.; Gasanly, N. M.The electrical resistivity and Hall coefficient of p-type TlGaTe2 crystals were measured in the temperature range of 110-320 K. The electrical resistivity, charge carrier density and Hall mobility data for the crystals have been analyzed by means of existing theories and models to determine the extrinsic energy levels, the carrier effective mass, the donor and acceptor concentrations and the dominant scattering mechanism in the crystal as well. The analysis of the temperature-dependent electrical resistivity recorded parallel and perpendicular to the crystal's axis ( c-axis) reflected the existence of energy levels located at 0.26 and at 0.20 eV, respectively. The difference of these two energy levels is due to crystal anisotropy. The energy level at 0.26 eV was found to represent an acceptor level, as confirmed from Hall data analysis. The temperature dependence of the carrier density was analyzed by using the single-donor-single-acceptor model. The latter analysis revealed the carrier effective mass and the acceptor and donor concentrations as 0.73m(0), 4.10 x 10(17) cm(-3) and 1.20 x 10(17) cm(-3), respectively. The Hall mobility of TlGaTe2 is found to be limited by the scattering of hole-acoustic phonon interactions. The calculated theoretical mobility fits to the experimental one under the condition that the acoustic deformation potential is 11.0 eV, which is the energy position of the top of valence band maximum that is formed by the Te 5s states.
