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Article Citation - WoS: 7Citation - Scopus: 7Design of the Zns/Ge pn Interfaces as Plasmonic, Photovoltaic and Microwave Band Stop Filters(Elsevier Science Bv, 2017) Alharbi, S. R.; Qasrawi, A. F.In the current work, we report and discuss the features of the design of a ZnS (300 nm)/Ge (300 nm)/GaSe (300 nm) thin film device. The device is characterized by the X-ray diffraction, electron microscopy, energy dispersive X-ray spectroscopy (EDS), optical spectroscopy, microwave power spectroscopy and light power dependent photoconductivity. While the X-ray diffraction technique revealed a polycrystalline ZnS coated with two amorphous layers of Ge and GaSe, the hot probe tests revealed the formation of pn interface. The optical spectra which were employed to reveal the conduction and valence band offsets at the ZnS/Ge and Ge/GaSe interface indicated information about the dielectric dispersion at the interface. The dielectric spectra of the ZnS/Ge/GaSe heterojunction which was modeled assuming the domination of surface plasmon interactions through the films revealed a pronounced increase in the drift mobility of free carriers in the three layers compared to the single and double layers. In the scope of the fitting parameters, a wave trap that exhibit filtering properties at notch frequency of 2.30 GHz was designed and tested. The ac signals power spectrum absorption reached similar to 99%. In addition, the photocurrent analysis on the ZnS/Ge/GaSe interface has shown it is suitability for photovoltaic and photosensing applications. (C) 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND licenseArticle Citation - WoS: 4Citation - Scopus: 5Thermoluminescence characteristics of GaSe and Ga2Se3 single crystals(Elsevier, 2022) Isik, M.; Sarigul, N.; Gasanly, N. M.GaSe and Ga2Se3 are semiconducting compounds formed from same constituent elements. These compounds have been attractive due to their optoelectronic and photovoltaic applications. Defects take remarkable attention since they affect quality of semiconductor devices. In the present paper, deep defect centers in GaSe and Ga2Se3 single crystals grown by Bridgman method were reported from the analyses of thermoluminescence measurements performed in the 350-675 K range. Experimental TL curves of GaSe and Ga2Se3 single crystals presented one and two overlapped peaks, respectively. The applied curve fitting and initial rise techniques were in good agreement about trap activation energies of 0.83 eV for GaSe, 0.96 and 1.24 eV for Ga2Se3 crystals. Crystalline structural properties of the grown single crystals were also investigated by x-ray diffraction measurements. The peaks observed in XRD patterns of the GaSe and Ga2Se3 crystals were well-consistent with hexagonal and zinc blende structures, respectively.Article Citation - WoS: 5Citation - Scopus: 5Structural and Optical Properties of Thermally Evaporated (gase)0.75-(gas)0.25 Thin Films(Elsevier Gmbh, 2021) Isik, M.; Işık, Mehmet; Emir, C.; Gasanly, N. M.; Işık, Mehmet; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics EngineeringGaSe and GaS binary semiconducting compounds are layered structured and have been an attractive research interest in two-dimensional material research area. The present paper aims at growing (GaSe)0.75 - (GaS)0.25 (or simply GaSe0.75S0.25) thin film and investigating its structural and optical properties. Thin films were prepared by thermal evaporation technique using evaporation source of its single crystal grown by Bridgman method. The structural properties were revealed using x-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. XRD pattern and EDS analyses indicated that thin films annealed at 300 ?C were successfully deposited and its structural characteristics are well-consistent with its single crystal form. Surface morphology was studied by means of SEM and AFM measurements. Optical properties were investigated by transmission and Raman spectroscopy techniques. Raman spectrum exhibited three peaks around 172, 242 and 342 cm-1. Analyses of transmission spectrum revealed the direct band gap energy as 2.34 eV. The mixed compounds of GaSe0.75S0.25 were prepared for the first time in a thin film form and the results of the present paper would provide valuable information to research area in which layered compounds have been studied in detail.Article Citation - WoS: 29Citation - Scopus: 28Optoelectronical Properties of Polycrystalline Β-Gase Thin Films(Wiley-v C H verlag Gmbh, 2006) Qasrawi, AF; Ahmad, MMSPolycrystalline beta-GaSe thin films were obtained by the thermal evaporation of GaSe crystals onto glass substrates kept at 300 degrees C under a pressure of 10(-5) Torr. The transmittance and reflectance of these films was measured in the incident photon energy range of 1.1-3.70 eV. The absorption coefficient spectral analysis in the sharp absorption region revealed a direct allowed transitions band gap of 1.83 eV. The data analysis allowed the identification of the dispersive optical parameters by calculating the refractive index in the wavelength region of 620-1100 nm. In addition, the photocurrent of the samples was studied as function of incident illumination-intensity and temperature. The photocurrent is found to exhibit sublinear and supralinear character above and below 270 K, respectively. The temperature dependent photocurrent data analysis allowed the calculation of photocurrent activation energies as 603, 119 and 45 meV being dominant in the temperature regions of 250-300 K, 180-240 K and 80-160 K, respectively. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Article Citation - WoS: 11Citation - Scopus: 10Optical Conduction in Amorphous Gase Thin Films(Elsevier Gmbh, 2016) Qasrawi, A. F.; Khanfar, Hazem. K.; Kmail, Renal R. N.In this work, the optical conduction mechanism in GaSe thin films was explored by means of dielectric spectral analysis in the 270-1000 THz range of frequency. The GaSe films which are found to be amorphous in nature are observed to follow the Lorentz approach for optical conduction. The modeling of the optical conductivity which takes into account the damped electronic motion resulting from the collision of photogenerated carriers with impurities, phonons and other damping sources allowed determining the optical conduction parameters. Particularly, an average carrier scattering time, a free carrier density, a reduced resonant frequency, a field effect mobility and an electron bounded plasma frequency of 0.142 (fs), 1.7 x 10(19) (cm(-3)), 875.8 (THz), 1.25 (cm(2)/Vs) and 82.8 (THz), respectively, were determined. These parameters are promising as they indicate the applicability of GaSe in the technology of mid-infrared plasmonic nanoantennas. In addition, the dielectric optical signal which displayed a resonance peak at 500 THz seems to be attractive for use in passive modes operating optoelectronic devices like field effect transistors as they exhibit an increasing signal quality factor with decreasing incident light frequency (C) 2016 Elsevier GmbH. All rights reserved.Article Citation - WoS: 45Citation - Scopus: 48Refractive Index, Band Gap and Oscillator Parameters of Amorphous Gase Thin Films(Wiley-v C H verlag Gmbh, 2005) Qasrawi, AF; Department of Electrical & Electronics EngineeringGaSe thin films are obtained by evaporating GaSe crystals onto ultrasonically cleaned glass substrates kept at room temperature under a pressure of similar to 10(-5) Torr. The X-ray analysis revealed that these films are of amorphous nature. The reflectance and transmittance of the films are measured in the incident photon energy range of 1.1-3.0 eV. The absorption coefficient spectral analysis revealed the existence of long and wide band tails of the localized states in the low absorption region. The band tails width is calculated to be 0.42 eV. The analysis of the absorption coefficient in the high absorption region revealed an indirect forbidden band gap of 1.93 eV. The transmittance analysis in the incidence photon wavelength range of 500-1100 nm allowed the determination of refractive index as function of wave length. The refractive index-wavelength variation leads to the determination of dispersion and oscillator energies as 31.23 and 3.90 eV, respectively. The static refractive index and static dielectric constant were also calculated as a result of the later data and found to be 9.0 and 3.0, respectively.Article Citation - WoS: 3Citation - Scopus: 4Structural and Optical Properties of the Zns/Gase Heterojunctions(Iop Publishing Ltd, 2017) Alharbi, S. R.; Abdallaha, Maisam M. A.; Qasrawi, A. F.In the current work, the ZnS/GaSe thin film heterojunction interfaces are experimentally designed and characterized by means of x-ray diffraction, scanning electron microscopy, energy dispersion spectroscopy and optical spectroscopy techniques. The heterojunction is observed to exhibit physical nature of formation with an induced crystallization of GaSe by the ZnS substrate. For this heterojunction, the hot probe technique suggested the formation of a p-ZnS/n-GaSe interface. In addition, the designed energy band diagram of the heterojunction which was actualized with the help of the optical spectrophotometric data analysis revealed a respective conduction and valence band offsets of 0.67 and 0.73 eV. On the other hand, the dielectric dispersion analysis and modeling which was studied in the frequency range of 270-1000 THz, have shown that the interfacing of the ZnS with GaSe strongly affects the properties of ZnS as it reduces the number of free carriers, shifts down the plasmon frequency, increases the charge carrier scattering time and results in higher values of drift mobility at Terahertz frequencies.Article Citation - WoS: 3Citation - Scopus: 3Structural, Compositional and Optical Properties of Gallium Selenide Thin Films Doped With Cadmium(Wiley-v C H verlag Gmbh, 2008) Qasrawi, A. F.; Saleh, A. A.Polycrystalline cadmium doped gallium selenide thin films were obtained by the thermal co-evaporation of GaSe crystals and Cd grains onto glass substrates. The structural, compositional and optical properties of these films have been investigated by means of X-ray diffraction, energy dispersive X-ray analysis and UV-visible spectroscopy techniques, respectively. Particularly, the elemental analysis, the crystalline nature, the energy band gap, the refractive index, the dispersion energy and static dielectric constant have been identified. The absorption coefficient spectral analysis in the sharp absorption region revealed a direct forbidden energy band gap of 1.22 eV. The cadmium doping has caused a significant decrease in the values of the energy band gap and in all the dispersive optical parameters, as well. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinbeim.Article Citation - WoS: 1Citation - Scopus: 1Temperature-Dependent Current-Voltage Characteristics of p-gase0.75< Heterojunction(Springer Heidelberg, 2023) Isik, M.; Surucu, O.; Gasanly, N. M.GaSe0.75S0.25 having layered structure is a potential semiconductor compound for optoelectronics and two-dimensional materials technologies. Optical and structural measurements of the GaSe0.75S0.25 thin film grown on the glass substrate showed that the compound has hexagonal structure and band energy of 2.34 eV. GaSe0.75S0.25 thin film was also grown on the silicon wafer and p-GaSe0.75S0.25/n-Si heterojunction was obtained. To make the electrical characterization of this diode, temperature-dependent current-voltage (I-V) measurements were carried out between 240 and 360 K. Room temperature ideality factor and barrier height of the device were determined from the analyses of I-V plot as 1.90 and 0.87 eV, respectively. Temperature-dependent plots of these electrical parameters showed that the ideality factor decreases from 2.19 to 1.77, while barrier height increases to 0.94 from 0.71 eV when the temperature was increased from 240 to 360 K. The conduction mechanism in the heterojunction was studied considering the Gaussian distribution due to presence of inhomogeneity in barrier height. The analyses presented the mean zero-bias barrier height, zero-bias standard deviation, and Richardson constant.
