Fathy A Abdel-Wahab - Academia.edu (original) (raw)

Papers by Fathy A Abdel-Wahab

Journal of Inorganic and Organometallic Polymers and Materials

PVA/PVP films doped with zinc sulphate heptahydrate (ZnSO4·7H2O) nanoparticles (NPs) are prepared... more PVA/PVP films doped with zinc sulphate heptahydrate (ZnSO4·7H2O) nanoparticles (NPs) are prepared using an in situ chemical method. Furthermore, as-prepared samples are irradiated with an electron beam at doses of 20, 25, 30, 35, and 40 kGy. Elemental analyses using energy dispersive X-ray spectroscopy (EDXS) of the fresh films showed the existence of both zinc oxide and zinc sulphide as main and minor phases in sequence. Moreover, scanning electron microscope measurements (SEM) revealed that embedded Zn NPs have regular and evenly distributed pores inside PVA/PVP network. On the other hand, the structural variations due to e-beam irradiation are monitored by a high-resolution-transmission electron microscope (HR-TEM), which displayed that encapsulated Zn NPs are well dispersed and capped inside PVA/PVP structural network. The measured optical absorption coefficient (α) of PVA/PVP/zinc sulphate nanocomposite films showed an increase against e-beam dose. Moreover, the calculated opti...

Materials Research Bulletin

Materials Letters, 2019

Herein, we present the results of high-performance visible light photodetector fabricated from th... more Herein, we present the results of high-performance visible light photodetector fabricated from the grown TlGaSSe single crystal for the first time. The growth direction was found to be (100) and layered structure was confirmed by scanning electron microscope (SEM) micrograph. The photocurrent observed to be increased with increasing the light intensity and voltage. The photo responsitivity (R), detectivity (D) and external quantum efficiency (EQE) were studied for the fabricated device. The maximum value of R is found to be ~ 980 mAV-1. The D value shows a decrease with increasing the light intensity and found in a range of 4.41x10 11 to 8.48x10 10 Jones. Further, the maximum value of EQE was found ~ 193% at a light intensity of 10 μWcm-2. Photoswitching behavior of the device was also studied and displayed that the ratio of on and off photo values ~ 45:100. The values of growth and decay time were found to be ~ 218 and 185 ms, respectively.

Radiation Physics and Chemistry, 2022

Optical and Quantum Electronics, 2021

of lead and borate glasses containing germanium and chromium oxide by composition 25B2O3-73.8PbO-... more of lead and borate glasses containing germanium and chromium oxide by composition
25B2O3-73.8PbO-xGeO2-(1.2 − x)Cr2O3, with 0 ≤ x ≤ 1.2 mol.%, are prepared. IR measurements are carried out to explore the structure of as-prepared samples. The convoluted IR peaks revealed presence of bridging oxygen up to x = 0.6 mol%. At x > 0.6 mol% none bridging oxygen is the dominant. The dependence of the measured hydrostatic density and corresponding molar volume for the studied compositions are analyzed and discussed. The dispersion curves of refractive index (n) and absorption index (k) are calculated in the spectral range 300–2500 nm. The effect of increasing the ratio GeO2/[GeO2 + Cr2O3] on the calculated dispersion energy, lattice energy, oscillator energy and material dispersion are deduced. For photonic applications, the wavelength at zero material dispersion for the investigated samples is calculated and compared with other systems based on Borates, silicates and Germinate fiber. The results recommend that the present glass could be used in different modern optoelectronics devices.

$Research paper thumbnail of Dispersion dependence of second-order refractive index and complex third-order optical susceptibility in oxide glasses$

Physics Letters A, 2009

A method correlates Fresnel-based spectrophotometric measurements and Lorentz dispersion theory i... more A method correlates Fresnel-based spectrophotometric measurements and Lorentz dispersion theory is presented to study the dispersion of nonlinear optical parameters in particularly oxide glasses in a very wide range of angular frequency. The second-order refractive index and third-order optical susceptibility of Cr-doped glasses are determined from linear refractive index. Furthermore, both real and imaginary components of the complex susceptibility are

Journal of Non-Crystalline Solids, 2008

Physica B-condensed Matter - PHYSICA B, 2005

Amorphous gallium arsenide (a-GaAs) films were prepared from their constituents using the co-evap... more Amorphous gallium arsenide (a-GaAs) films were prepared from their constituents using the co-evaporation technique. The temperature dependence of DC conductivity for the as-deposited (fresh) As-rich and that of thermally annealed films over the temperature range 373 553 K is measured. Results of the characteristic electrical parameters indicate non-monotonic behavior during the thermal annealing range 373 423 K and a monotonic one in the range 423 553 K. Results of the density of structural defect states, using the space-charge-limited current model, are given and discussed in relation to the nature and distribution of defect states regarding their dependence on the thermal treatment.

Journal of Physics and Chemistry of Solids, 2007

Chalcogenide Letters, 2010

The optical transmission T(λ) as well as the reflection R(λ) spectra has been recorded, in the sp... more The optical transmission T(λ) as well as the reflection R(λ) spectra has been recorded, in the spectral range of 500-2500 nm, for thermally deposited Sm doped a-Se films. The Xray diffraction technique was used to critically identify the structural nature of the studied films. The current optical theories and models were applied to analyze the recorded spectra and to calculate various interesting optical parameters. These include: dispersion of the two components of both complex refractive index (ik n n − =) and complex dielectric constant (ε 1 and ε 2), energy gap (E g), Urbach energy (E u), single oscillator energy (E o), lattice oscillating strength (E 1), material dispersion M(λ) and the wavelength at zero material dispersion (λ c). At this point, a similar non-monotonic trend is observed for the compositional dependence of various parameters. This has been ascribed to the disorder and/or structural defects introduced due to the incorporation of Sm, up to 0.008 % Sm, in the a-Se matrix. Besides, a trial has been made thus estimating the inter-band transitions for the Se-Sm samples investigated.

Applied Surface Science, 2009

Selenium (Se) films implanted with Dysprosium (Dy) atoms are prepared using thermal evaporation t... more Selenium (Se) films implanted with Dysprosium (Dy) atoms are prepared using thermal evaporation technique. The temperature dependence of ac conductivity measured in frequency range 50 Hz-80 KHz is found to be proportional to ωs This proportionality is reasonably well interpreted, in the low temperature region, by correlated barrier hopping (CBH), of bi-polaron between both random and paired defect states. In the same time the high temperature part the ac conductivity is well fitted using Mayer-Neldel rule. Furthermore, the dielectric relaxation times of the doped a-Se films are determined from the dependence of the loss factor on the applied frequency relations. The Cole-Cole diagrams have been presented and are used to determine the values of the static and optical dielectric constants of a-Se doped with Dy atoms.

PVA/H2SO4/Ethanol doped with Silver nano-composite films are prepared using in-situ reduction met... more PVA/H2SO4/Ethanol doped with Silver nano-composite films are prepared using in-situ reduction method. The fresh samples are irradiated to Gamma rays with doses 0, 10, 20, 30, 40, and 50 kGy. The structural characterizations of as-prepared films are studied using XRD and UV absorbance techniques. The diffraction by X-ray revealed existence of Ag2O and Ag nano-particles, in the structural matrix of PVA, in the form of phase centered cubic structure. Furthermore, the fitted optical absorbance and measurements performed by HR-TEM illustrated that the embedded Ag nano-particles has a quasi-spherical shape with an average diameter ~25 nm. Furthermore, fitting the measured absorption coefficients revealed that the direct optical energy gap is the most probable transition. The wavelength at zero material dispersion showed an increase from 1.1578 μm up to 1.6410 μm against the irradiation dose. This means that nano-composites could be used to transmit optical data in low dispersion optical f...

The dielectric parameters of Sm doped Se films (namely SeSm0.008) films prepared by thermal evapo... more The dielectric parameters of Sm doped Se films (namely SeSm0.008) films prepared by thermal evaporation were measured under vacuum in a wide range of frequency and temperature. The measured real part of the admittance (Y') versus frequency (f) were analyzed and shows two distinct regions. In the first one which lie in the low frequency range Y' displayed an independence on the frequency that give a direct evidence for the existence of Debye model. In the high frequency part, which is considered using power low: (n ≤ 1.0), a deviation from Debye model is observed where Y' increase linearly against frequency. Analysis of the calculated values of n with reference to those numerically calculated for different theoretical a.c. conduction models shows that correlated barrier hopping (CBH) is a fairly good to describe the dominant conduction mechanism. The equivalent circuit approach is applied by comparing the theoretical and experimental data trends of the plots of Z'-Z a...

A series of ternary phosphate glass system, required for IR photonic applications, is synthesized... more A series of ternary phosphate glass system, required for IR photonic applications, is synthesized by the melt-quenching technique. The effect of replacing ZnO (divalent) with Na2O (monovalent) on some optoelectronic properties of the prepared glass system, such as band gap energy and exciton-phonon coupling, is investigated. The dependence of composition on the two-photon absorption coefficient is inferred over a wavelength range of 0.2-2.5 μm. The exciton excitation mechanism is discussed by applying Elliott’s model which indicates a direct electronic interband transition. Chemical bond approach is applied to analyze and explain the obtained results and their effect on the glass properties.

Biomedical Physics & Engineering Express, 2016

American Journal of Optics and Photonics, 2014

Photonics properties of glasses can be designed by controlling their complex Kerr nonlinearity. C... more Photonics properties of glasses can be designed by controlling their complex Kerr nonlinearity. Chemical structure and bonding properties are considered as the origin of glass third-order susceptibilities. Investigation of the role of orbital hybridization on the glass electronic polarizability and third-order susceptibility is carried out. Thus, series of heavy metal lead borate glass of the composition 0.25B 2 O 3-0.75PbO is prepared by melt quenching technique. Orbital hybridization, as a linear combination for valence electron wave functions of p-and d-block elements, is obtained through structural co-substitution of very small contents of Cr 2 O 3 and/or SeO 2 , by B 2 O 3. It get succeed to tune the glass nonlinear optical characteristics such as; the complex components of third-order susceptibility. Scaling roles describing the relations between oxide ion polarizability and index of refraction and between imaginary part of third-order susceptibility and band gap energy are proposed. The glasses exhibit zero-dispersion wavelength at 1.55 µm band which is needed for telecommunication devices. The polarizability approach is applied to analyze and explain the obtained glass properties.