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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: 7Citation - Scopus: 7Plasmon-Electron Dynamics at the Au/Inse and Y/Inse Interfaces Designed as Dual Gigahertz-Terahertz Filters(Elsevier Gmbh, Urban & Fischer verlag, 2017) Alharbi, S. R.; Qasrawi, A. F.In this work, the X-ray diffraction, the Scanning electron microscopy, the energy dispersive X-ray, the Raman, The UV-vis light and the impedance spectral techniques are employed to explore the structural, vibrational, optical and electrical properties of the Au/InSe and Y/InSe thin film interfaces. It was shown that with its amorphous nature of crystallization, the InSe thin films exhibited n-type conductivity due to the 3% excess selenium. For this form of InSe, the only active Raman spectral line is 121 (cm(-1)). In addition to the design of the energy band diagram, the analysis the dielectric spectra and the optical conductivities were possible in the frequency range of 270-1000 THz. The modeling of the optical conductivities of the Au, Y, Au/InSe and Y/InSe with the help of Lorentz approach for optical conduction, assured that the conduction is dominated by the resonant plasmon-electron interactions at the metals and metals/semiconductors interfaces. It also allowed tabulating the necessary parameters for possible applications in terahertz technology: These parameters are the electron effective masses, the free electron densities, the electron bounded plasmon frequencies, the electron scattering times, the reduced resonant frequencies and the drift mobilities. On the other hand, the impedance spectral analysis of the Y/InSe/Au interfaces in the frequency range of 0.01-1.80 GHz, revealed negative capacitance effect associated with band filter features that exhibit maximum transition line at 1.17 GHz. This value nominates the interface as a member of filter classes in the gigahertz technology. (C) 2017 Elsevier GmbH. All rights reserved.Article Citation - WoS: 15Citation - Scopus: 17Dielectric Dispersion in Ga2s3< Thin Films(Springer, 2017) Alharbi, S. R.; Qasrawi, A. F.In this work, the structural, compositional, optical, and dielectric properties of Ga2S3 thin films are investigated by means of X-ray diffraction, scanning electron microscopy, energy dispersion X-ray analysis, and ultraviolet-visible light spectrophotometry. The Ga2S3 thin films which exhibited amorphous nature in its as grown form are observed to be generally composed of 40.7 % Ga and 59.3 % S atomic content. The direct allowed transitions optical energy bandgap is found to be 2.96 eV. On the other hand, the modeling of the dielectric spectra in the frequency range of 270-1,000 THz, using the modified Drude-Lorentz model for electron-plasmon interactions revealed the electrons scattering time as 1.8 (fs), the electron bounded plasma frequency as similar to 0.76-0.94 (GHz) and the reduced resonant frequency as 2.20-4.60 x10(15) (Hz) in the range of 270-753 THz. The corresponding drift mobility of electrons to the terahertz oscillating incident electric field is found to be 7.91 (cm (2)/Vs). The values are promising as they nominate the Ga2S3 thin films as effective candidates in thin-film transistor and gas sensing technologies.Review Citation - WoS: 65Citation - Scopus: 73Micro Tool Design and Fabrication: a Review(Elsevier Sci Ltd, 2018) Oliaei, S. N. B.; Karpat, Y.; Paulo Davim, J.; Perveen, A.Mechanical micromachining is considered as a cost-effective and efficient fabrication technique to produce three dimensional features and free-form surfaces from various engineering materials. Micro cutting tools are an essential part of mechanical micromachining and they are exposed to harsh conditions which reduces tool life and adversely affect the economics of the process. The challenge is therefore to maintain the tool rigidity and cutting edge sharpness for extended period of time. Thus, the design, fabrication and durability of micro cutting tools are of significant importance for successful micromachining operations. This review paper aims to provide a comprehensive understanding about the capabilities, characteristics, and limitations of different fabrication techniques used in the manufacturing of micro cutting tools. State-of-the-art micro cutting tool design and coating technology has been presented for various micromachining applications. Possible future research direction and development in the field of micro tool design and fabrication has also been discussed.Article Citation - WoS: 6Citation - Scopus: 6Gold and Ytterbium Interfacing Effects on the Properties of the Cdse/Yb Nanosandwiched Structures(Elsevier Science Bv, 2018) Alharbi, S. R.; Qasrawi, A. F.Owing to the performance of the CdSe as an optoelectronic material used for the production of quantum dots, photosensors and wave traps we here, in this article, report the enhancements in structural and electrical properties that arises from the nanosandwiching of a 40 nm thick Yb film between two films of CdSe (CYbC-40). The CdSe films which were deposited onto glass, Yb and Au substrates are characterized by X-ray diffraction, temperature dependent electrical conductivity and impedance spectroscopy measurements in the frequency range of 10-1800 MHz. The analysis of the XRD patterns have shown that the glass/CdSe/Yb/CdSe films exhibit larger grain size and lower strain, defect density and lower stacking faults compared to the not sandwiched CdSe. In addition, it was observed that the Yb shifts the donor states of the n-type CdSe from 0.44 to 0.29 eV leading to a modification in the built in voltage of the material. On the other hand, the design of the energy band diagram has shown the ability of the formation of the Au/CYbC-40/Yb as Schottky (SB) and the Au/CYbC-40/Au as back to back Schottky barriers (BBSB). While the SB device show low band pass filter characteristics, the BBSB device performed as band stop filters. The BBSB device exhibited negative capacitance effects with filtering features that reveal a return loss of 42 dB at similar to 1440 MHz.Article Citation - WoS: 4Citation - Scopus: 4Band Offsets and Optical Conduction in the Cdse/Gase Interface(Elsevier Science Bv, 2016) Kayed, T. S.; Qasrawi, A. F.; Elsayed, Khaled A.In this work, the design and characterization of CdSe/GaSe heterojunction is considered. The CdSe/GaSe thin film interface was prepared by the physical vapor deposition technique. Systematic structural and optical analysis were performed to explore the crystalline nature, the optical band gaps, the conduction and valence band offsets, the dielectric spectra, and the frequency dependent optical conductivity at terahertz frequencies. The X-ray diffraction analysis revealed a polycrystalline interface that is mostly dominated by the hexagonal CdSe oriented in the (002) direction. It was also found that the CdSe/GaSe interface exhibits conduction and valence band offsets of 1.35 and 1.23/1.14 eV, respectively. The dielectric spectra displayed two dielectric resonance peaks at 530 and 445 THz. Moreover, the computational fittings of the optical conductivity of the interface revealed a free carrier scattering time of 0.41 (fs) for a free carrier density of 7.0 x 10(18) (cm(-3)). The field effect mobility for the CdSe/GaSe interface was found to be 5.22 (cm(2)/Vs). The remarkable features of this device having large band offsets and qualitative optical conduction dominated by a scattering time in the order of femtoseconds in addition to the dielectric property nominate the device to be used in optoelectronic technology. (C) 2016 Elsevier B.V. All rights reserved.Article Citation - WoS: 6Citation - Scopus: 6Al/Cdse Resonant Tunneling Thin Film Transistors(Elsevier Science Bv, 2017) Qasrawi, A. F.; Kayed, T. S.; Elsayed, Khaled A.An Al/CdSe/GaSe/C thin film transistor device was prepared by the physical vapor deposition technique at a vacuum pressure of 10(-5) mbar. The x-ray diffraction measurements demonstrated the polycrystalline nature of the surface of the device. The de current-voltage characteristics recorded for the Al/CdSe/C and Al/CdSe/GaSe/C channels displayed a resonant tunneling diode features during the forward and reverse voltage biasing, respectively. In addition, the switching current ratio of the Al/CdSe/C increased from 18.6 to 9.62x10(3) as a result of the GaSe deposition on the CdSe surface. Moreover, the alternating electrical signal analyses in the frequency range of 1.0 MHz to 1.8 GHz, showed some remarkable properties of negative resistance and negative capacitance spectra of the AVCdSe/GaSe/C thin film transistors. Two distinct resonance-antiresonance phenomena in the resistance spectra and one in the capacitance spectra were observed at 0.53, 1.04 and 1.40 GHz for the Al/CdSe/C channel, respectively. The respective resonating peak positions of the resistance spectra shift to 0.38 and 0.95 GHz when GaSe is interfaced with CdSe. These features of the thin film transistors are promising for use in high quality microwave filtering circuits and also for use as ultrafast switches.Article Citation - WoS: 9Citation - Scopus: 8Dielectric dispersion in InSe/CdS bilayers(Elsevier Science Bv, 2018) Qasrawi, A. F.; Shehada, Sufyan R.In the current study, the effect of the amorphous InSe thin film substrate on the structural, optical and dielectric properties of CdS are investigated. The structural analysis of the bilayers indicated a strained growth of CdS onto InSe leading to decrease in grain size and increase in the dislocation density. The optical measurements have shown that the InSe/CdS exhibits two direct allowed transitions energy band gap values of 2.04 and 1.38 eV, in the high and low absorption regions, respectively. On the other hand, the detailed analysis of the dielectric spectra for the InSe, CdS and InSe/CdS layers has shown that the presence of the InSe substrate significantly improves the optical conduction parameters. Particularly, the Drude-Lorentz modeling for these dielectric systems revealed a drift mobility value of 329 cm(2)/V for the InSe/CdS bilayer. The deposition of the CdS onto InSe is also observed to shift the plasmon frequency of CdS from 2.49 to 0.77 GHz. The general features of the InSe/ CdS as plasmon cavities are promising as it shows its usability for production of optoelectronic devices that exhibit high performance at very high frequencies.Article Citation - WoS: 10Citation - Scopus: 10Post Annealing Effects on the Structural, Compositional, Optical and Dielectric Properties of Cd Doped Gase Thin Films(Elsevier Science Sa, 2015) Al Garni, S. E.; Qasrawi, A. F.In this work, the heat treatment effects at temperatures (T-a) of 200, 300 and 400 degrees C on the compositional, structural, optical and dielectric properties of Cd doped GaSe are explored by means of energy dispersive X-ray spectroscopy, X-ray diffraction and UV-VIS spectrophotometry. The annealing process of the Cd doped GaSe thin films revealed a highly oriented orthorhombic structure type that exhibit a systematic increase in the grain size. While the strain, degree of orientation and dislocation density of the annealed films are weakly affected by the annealing process. The optical energy band gap of the doped films decreased from 1.23 to 0.90 eV and the exponential energy band tails rose from 0.16 to 0.23 eV when the annealing temperature is raised from 300 to 400 degrees C. In addition, the analysis of the dielectric spectral curves which were studied in the frequency range of 270-1500 THz, allowed to investigate the oscillator and dispersion energies and the static (epsilon(s)) and lattice (epsilon(l)) dielectric constants. The annealing process on the doped samples decreased the dispersion and oscillator energies as well as es. Oppositely, el values increased from 12.52 to 24.45 as a result of larger grain size and less defect density associated with annealing process when T-a is raised from 200 to 400 degrees C, respectively. (C) 2015 Elsevier B.V. All rights reserved.Article Citation - WoS: 1Citation - Scopus: 1Structural, Optical and Electrical Properties of Ybinse Thin Films(Elsevier Science Sa, 2016) Alharbi, S. R.; Qasrawi, A. F.In this work, the compositional, the structural, the vibrational, the optical and the electrical characterizations of the YbInSe compound are investigated by means of energy dispersion X-ray analysis, scanning electron microscopy and X-ray diffraction, Raman spectroscopy, ultraviolet-visible light spectrophotometry, impedance spectroscopy and temperature dependent electrical conductivity, respectively. The 300 nm thick YbInSe films which were prepared by the co-evaporation of the source materials under a vacuum pressure of 10(-5) mbar, are observed to exhibit nanocrystalline clusters of size of 27 nm regularly distributed among an amorphous structure. The most intensive Raman active lines are observed at 150 and 254 cm(-1). In addition, the optical analysis has shown that the films exhibit a direct forbidden electronic transitions type energy band gap of 1.07 eV. The optical transitions are associated with interband tail states of width of 0.28 eV. Moreover, the real and imaginary parts of dielectric spectra which were analyzed in the frequency range of 270-1000 THz, were analyzed in accordance with the single oscillator and the Lorentz models, respectively. The modeling allowed determining the oscillator and dispersion energies, the terahertz free carrier scattering time, the free holes effective mass, the carrier density, the drift mobility and the reduced resonant frequency for the YbinSe films. In the electronic part of study, the temperature dependent dc electrical conductivity analysis, indicated the domination of the variable range hopping transport mechanism below 335 K, the thermal excitation of charge carriers in the range of 337390 K and the extrinsic-intrinsic transition property at 390 K. The ac conductivity spectra which were recorded in the frequency range of 10-1500 MHz, revealed the domination of the correlated barrier hopping of free carriers between pairs of localized states at the Fermi level. (C) 2016 Elsevier B.V. All rights reserved.
