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Article Citation - WoS: 1Citation - Scopus: 1Pseudodielectric Dispersion in As2se3< Thin Films(Wiley-v C H verlag Gmbh, 2020) Kayed, Tarek S.; Kayed, Tarek Said; Qasrawi, Atef F.; Qasrawı, Atef Fayez Hasan; Kayed, Tarek Said; Qasrawı, Atef Fayez Hasan; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics EngineeringHerein, X-ray diffraction, energy dispersive X-ray spectroscopy, and spectral ellipsometry techniques are used to investigate the structural, pseudo-optical, and pseudodielectric properties of arsenic selenide thin films. The stoichiometric films which are prepared by the thermal evaporation technique are found to prefer the amorphous nature of growth. While the pseudoabsorption coefficient spectra display strong absorption bands at 1.84, 1.81, 1.41, and 1.13 eV, the preferred pseudo-optical transitions happen within a direct forbidden energy bandgap of 1.80 eV. In addition, the real part of the pseudodielectric spectra displays three strong resonance peaks at critical energy values of 2.33, 1.90, and 1.29 eV. Modeling of the imaginary part of the pseudodielectric constant spectra in accordance with the Drude-Lorentz approach results in the existence of six linear oscillators. The response of arsenic selenide to elliptically polarized light signals shows that the films exhibit drift mobility, free electron concentration, and plasmon frequency values in the ranges of 0.21-43.96 cm(2) V(-1)s(-1), 1.90-58.0 x 10(19) cm(-3), and 5.8-32.0 GHz, respectively. The optical conductivity parameters for As2Se3 film nominate it as a promising candidate for the fabrication of tunneling diodes suitable for microwaves filtering up to 32.0 GHz and as thin-film transistors.Article Citation - WoS: 4Citation - Scopus: 4Determination of Carrier Effective Mass, Impurity Energy Levels, and Compensation Ratio in Ga4se3< Layered Crystals by Hall Effect Measurements(Wiley-v C H verlag Gmbh, 2008) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Gasanly, N. M.; Qasrawı, Atef Fayez Hasan; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics EngineeringIn this work, the dark electrical resistivity, charge carriers density and Hall mobility of Ga4Se3S single crystals have been measured and analyzed in the temperature region of 200-350 K. The data analyses have shown that this crystal exhibits an extrinsic n-type of conduction. The temperature-dependent dark electrical resistivity analysis reflected the existence of energy level as 0.31 eV. The temperature dependence of carrier density was analyzed by using the single donor-single acceptor model. The latter analysis allowed the determination of electron effective mass as 0.38m(0), hole effective mass as 0.42m(0), donor impurity energy level as 0.45 eV, acceptor-donor concentration ratio (N-a/N-d) as 0.97 and a donor-acceptor concentration difference as N-d - N-a = 1.5 x 10(11) cm(-3). The Hall mobility of Ga4Se3S is found to increase with decreasing temperature following a power law of slope of similar to(-6.3). The abnormal behavior of mobility was attributed to the domination of phonon scattering and/or crystals anisotropy. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
