3 results
Search Results
Now showing 1 - 3 of 3
Article Citation - WoS: 9Citation - Scopus: 9Optical Dynamics in the Ag/Α-ga2< Layer System(Elsevier Sci Ltd, 2018) Alharbi, S. R.; Qasrawi, A. F.In this work, thin films of Ga2S3 are deposited onto 150 nm thick transparent Ag substrate by the physical vapor deposition technique under vacuum pressure of 10(-5) mbar. The films are studied by the X-ray diffraction and optical spectrophotometry techniques. It is found that the Ag substrate induced the formation of the monoclinic alpha-Ga2S3 polycrystals. The transparent Ag substrate also changed the preferred optical transition in Ga2S3 from direct to indirect It also increased the light absorption by 79 and 23 times at incident light energies of 2.01 and 2.48 eV, respectively. In addition, a red shift in all types of optical transitions is observed. Some the extended energy band tails of Ag appears to form interbands in the band gap of Ga2S3. These interbands strongly attenuated the dielectric and optical conduction parameters. Particularly, an enhancement in the dielectric constant values and response to incident electromagnetic field is observed. The Drude-Lorentz modeling of this interface has shown that the free carrier density, drift mobility, plasmon frequency and reduced electron-plasmon frequency in Ga2S3 increases when the Ag substrate replaced the glass or other metals like Yb, Al and Au. The nonlinear optical dynamics of the Ag/Ga2S3 are promising as they indicate the applicability of this interface for optoelectronic applications.Article Citation - WoS: 3Citation - Scopus: 3Observation of in Situ Enhanced Crystallization, Negative Resistance Effect and Photosensitivity in Tl2ingase4< Crystals(Elsevier Sci Ltd, 2021) Qasrawi, A. F.; Irshaid, Tahani M. A.; Gasanly, N. M.In this work, we report the properties of Tl2InGaSe4 crystals as multifunctional material. Namely, Tl2InGaSe4 crystals are grown by the modified Bridgman method using mixtures of TlInSe2 (50%) and TlGaSe2 (50%) single crystals. The enhanced crystallization and structural stabilities are monitored by the X-ray diffraction technique during the in situ heating and cooling cycles. The structural analyses on the Tl2InGaSe4 crystals revealed domination of both of the monoclinic and tetragonal phases in the crystals. In addition, the produced crystals are used to fabricate Schottky diodes. While the scanning electron microscopy has shown that the crystals are composed of layered nanosheets, the electrical analyses have shown that the crystals exhibit light photosensitivity of 12.7 under tungsten light illumination of 10 kLuxes. The attenuation in the electrical parameters of the Ag/Tl2InGaSe4/C diodes presented by series resistance, barrier height and ideality factor upon light excitations make them promising for applications in optoelectronics as switches and photodetectors. Moreover, the alternating electrical signals analyses on the capacitance spectra displayed resonance -antiresonance oscillations in the frequency domain of 83-100 MHz. The resistance spectra also exhibited negative resistance effect in the range of 55-135 MHz. These features of the device make it suitable for use as microwave resonators and memory devices as well.Article Citation - WoS: 1Citation - Scopus: 1Characterization of T1ins1.8se0.2 as Advanced Functional Crystals(Elsevier Sci Ltd, 2018) Qasrawi, A. F.; Atatreh, Areen A. M.; Gasanly, N. M.In this work, selenium doped TlInS1.8Se0.2 crystals are used to fabricate multifunctional devices that can handle more than one duty at a time. After revealing the morphological, compositional, structural and optical properties of the doped crystal, it is sandwiched between Ag and carbon metals. The crystals are characterized by means of ultraviolet-visible light spectrophotometry, impedance spectroscopy and illumination dependent current-voltage characteristics techniques. While the optical spectroscopy allowed determining the energy band gap of the crystals as well as the optical conductivity in the terahertz frequency domain, the impedance spectroscopy allowed identifying the conductance and reflectance spectra in the gigahertz frequency domain. The two techniques reveal promising characteristics presented by optical switching at 2.20 eV and band pass filtering properties in mega/gigahertz frequency domains. On the other hand, the analysis of the current (I)- voltage (V) characteristics which are recorded in the dark and under photoexcitation of unfiltered tungsten light in the light power range of 25-130 mW, revealed light intensity dependent rectifying properties. Particularly, the modeling of the experimental I-V curves in accordance with the Richardson Schottky and Chueng's theoretical approaches have shown that the Schottky diode ideality factor, series resistance and barrier height decreases with increasing light power. Such behavior indicates wide tunability of the device when used as photosensors. With the features presented by small size, photosensitivity, gigahertz/terahertz spectral responses, the device can be promising element for use in visible light and microwave communications.
