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Öğe Boosting the efficiency of Cu2ZnSnS4 solar cells with VO2 phase transition photonic crystal(Elsevier, 2023) Basyooni, Mohamed A.; Houimi, Amina; Tihtih, Mohammed; Zaki, Shrouk E.; Boukhoubza, Issam; Belaid, Walid; En-nadir, RedouanePhotonic crystal (PhC) has been studied for their potential to improve the efficiency of Cu2ZnSnS4 solar cells by increasing the generated photocurrent by integrating it as a back reflector with almost zero transmission through the absorption active zone of the solar cell. It was found that the thickness of PhC layers greatly affects the width of the photonic bandgap and that increasing the thickness of VO2 causes it to shift to a higher wavelength range. The PhC layers were added at the back side of the solar cell in two different configurations: (Monoclinic (M) VO2/TiO2) and (Tetragonal (T) VO2/TiO2) via SCAPS model. The study found that the (M VO2/TiO2) configuration led to an enhancement of the device's efficiency from 11.02 to 12.79%, while the (T VO2/TiO2) reaches 16.88%. The study concluded that the PhC layers enhance the light-matter coupling and photonic coupling and improvement in the device's performance.Öğe Development of Yttrium-Doped BaTiO3 for Next-Generation Multilayer Ceramic Capacitors(Amer Chemical Soc, 2023) Tihtih, Mohammed; Ibrahim, Jamal Eldin F. M.; Basyooni, Mohamed A.; En-nadir, Redouane; Belaid, Walid; Hussainova, Irina; Kocserha, IstvanThe use of electronic devices that incorporate multilayer ceramic capacitors (MLCCs) is on the rise, requiring materials with good electrical properties and a narrow band gap. This study synthesized yttrium-substituted barium titanate (Ba1-xYxTiO3, BYT) using a sol-gel process at 950 degrees C with varying concentrations of yttrium (0 < x < 0.3). X-ray diffraction analysis showed that the tetragonal phase became less pronounced as the yttrium content increased. The samples had varying grain sizes and porosity, with the BY30%T sample having the narrowest band gap at 2.21 eV. The BYT ceramic with 30% yttrium had a thermal conductivity of up to 7 W/m K and an electrical conductivity down to 0.002 (omega cm)-1 at 180 degrees C. The current-voltage characteristics of the BYT MLCC were also studied, showing potential use in next-generation high-capacity MLCCs. This work presents BYT as a promising material for these types of capacitors.Öğe Effect of in-/ex-situ annealing temperature on the optical, structural and gas sensing dynamics of CdS nanostructured thin films(Academic Press Ltd- Elsevier Science Ltd, 2020) Gormez, Arife Efe; Basyooni, Mohamed A.; Zaki, Shrouk E.; Eker, Yasin Ramazan; Sonmez, Erdal; Yilmaz, MucahitEffect of in-/ex-situ annealing on the structure, optical, photoluminescence, electrical characterization and gas sensing dynamics on CdS thin films are presented. Raman characterizations showed an increase in the peak intensity with increasing the annealing temperature under ex-situ, while a lower peak intensity observed through the in-situ annealing condition. No shift was observed in the Photoluminescence peaks through the yellow band peaks of in-situ annealed samples, however, a slightly blue shift was observed through the ex-situ annealed samples. High conductivity was observed for all samples, while in the case of in-situ RT, in-situ 100 degrees C, ex-situ 200 degrees C and ex-situ 300 degrees C, a CO2 and O-2 gas sensing activity have been tested. The ex-situ 300 degrees C sample shows a higher response towards CO2 compared with the ex-situ 200 degrees C film. While, both in-situ RT and 100 degrees C sensors show the same response towards CO2 with a high gas response. However, the in-situ 100 degrees C sensor has the highest response compared to in-situ RT film with a high response of 25% at 50 sccm towards O-2.Öğe Efficient MoWO3/VO2/MoS2/Si UV Schottky photodetectors; MoS2 optimization and monoclinic VO2 surface modifications(Nature Portfolio, 2020) Basyooni, Mohamed A.; Zaki, Shrouk E.; Shaban, Mohamed; Eker, Yasin Ramazan; Yilmaz, MucahitThe distinctive properties of strongly correlated oxides provide a variety of possibilities for modulating the properties of 2D transition metal dichalcogenides semiconductors; which represent a new class of superior optical and optoelectronic interfacing semiconductors. We report a novel approach to scaling-up molybdenum disulfide (MoS2) by combining the techniques of chemical and physical vapor deposition (CVD and PVD) and interfacing with a thin layer of monoclinic VO2. MoWO3/VO2/MoS2 photodetectors were manufactured at different sputtering times by depositing molybdenum oxide layers using a PVD technique on p-type silicon substrates followed by a sulphurization process in the CVD chamber. The high quality and the excellent structural and absorption properties of MoWO3/VO2/MoS2/Si with MoS2 deposited for 60 s enables its use as an efficient UV photodetector. The electronically coupled monoclinic VO2 layer on MoS2/Si causes a redshift and intensive MoS2 Raman peaks. Interestingly, the incorporation of VO2 dramatically changes the ratio between A-exciton (ground state exciton) and trion photoluminescence intensities of VO2/(30 s)MoS2/Si from < 1 to > 1. By increasing the deposition time of MoS2 from 60 to 180 s, the relative intensity of the B-exciton/Aexciton increases, whereas the lowest ratio at deposition time of 60 s refers to the high quality and low defect densities of the VO2/(60 s)MoS2/Si structure. Both the VO2/(60 s)MoS2/Si trion and A-exciton peaks have higher intensities compared with (60 s) MoS2/Si structure. The MoWO3/VO2/(60 s) MoS2/Si photodetector displays the highest photocurrent gain of 1.6, 4.32 x 10(8) Jones detectivity, and similar to 1.0 x 10(10) quantum efficiency at 365 nm. Moreover, the surface roughness and grains mapping are studied and a low semiconducting-metallic phase transition is observed at similar to 40 degrees C.Öğe Enhanced optical and thermal conductivity properties of barium titanate ceramic via strontium doping for thermo-optical applications(Springer, 2023) Tihtih, Mohammed; Ibrahim, Jamal Eldin F. M.; Basyooni, Mohamed A.; En-nadir, Redouane; Belaid, Walid; Abdelfattah, Mohamed M.; Hussainova, IrinaIn this study, we prepared a homogeneous fine powder of barium titanate (BaTiO3, BT) doped with different concentrations of strontium (x = 0, 0.05, 0.125, 0.15, 0.20, and 0.3) and having the composition Ba1-xSrxTiO3 (barium strontium titanate, BSrxT). XRD patterns and Rietveld refinement revealed the existence of a single tetragonal phase structure for BSrxT, x = 0-20%, and a single cubic structure for BSr30%T. The physical properties of the pure and doped mixtures were studied. The results showed that the addition of strontium to the physical properties of BaTiO3, including the apparent porosity, bulk density, linear shrinkage, and water absorption have been changed when increasing the Sr content. Moreover, the inclusion of 15% Sr in BaTiO3 increases the apparent porosity and water absorption of the sample to 6.2 and 28.5%, respectively. The optical properties were investigated by Ultraviolet-visible spectroscopy and it was found that the optical band gap decreases significantly with increasing Sr concentration, from 3.10 for pure BaTiO3 to 2.46 eV for the BSr30%T compound. The thermal conductivity measurements showed that the doping mechanism and the increased temperature have a significant effect on the thermal conductivity results of the fabricated ceramic materials. Therefore, it was found that the value of thermal conductivity increases with increasing Sr doping and at higher temperatures. A correlated behavior of optimum values is observed in band gap energy, absorption, and thermal conductivity which can be exploited for thermo-optical applications.Öğe Fast optoelectronic gas sensing with p-type V2O5/WS2/Si heterojunction thin film(Elsevier Science Sa, 2023) Basyooni, Mohamed A.; Zaki, Shrouk E.; Eker, Yasin RamazanThe efficiency of ultraviolet (UV) illumination in gas adsorption/desorption is remarkable due to its capacity to activate and energize CO2 molecules, rendering them more reactive and prone to surface interactions. A heterojunction device for room-temperature optoelectronic gas sensing has been fabricated. This was achieved through the deposition of an orthorhombic vanadium pentoxide (V2O5) thin film onto a wafer scale 2D p-type tungsten disulfide (WS2)/silicon (Si). The incorporation of the V2O5 layer brings about alterations in WS2's electronic properties, resulting in increased energy states for photo-generated carriers and a promising approach to enhance the intensity of exciton and trion peaks. Specifically, the WS2 film exhibits a carrier concentration of 3.67 x 1018 cm-3, while incorporating the V2O5 layer significantly raises this concentration to 1.20 x 1020 cm-3. The experiments reveal a rapid response time of 0.4 s and a recovery time of 0.2 s, respectively, demonstrating the swift desorption capability of the device in a CO2 environment. Remarkably, this device exhibits high optoelectronic performances, boasting a detectivity of 1.22 x 1013 Jones and a responsivity of 177.21 A/W. These findings have the potential to advance the development of improved gas-sensing devices, offering heightened sensitivity and selectivity in diverse optoelectronic applications.Öğe Fast response of CO2 room temperature gas sensor based on Mixed-Valence Phases in Molybdenum and Tungsten Oxide nanostructured thin films(Elsevier Sci Ltd, 2020) Basyooni, Mohamed A.; Zaki, Shrouk E.; Ertugrul, Sezin; Yilmaz, Mucahit; Eker, Yasin RamazanMolybdenum - tungsten oxide (Mo1-xWxO3, x = 1, 0.8, and 0.6) nanostructured thin films-based room temperture (RT) gas sensors are prepared by means of reactive RF magnetron co-sputtering at 400 degrees C. The structural, morphology, topography, optical, and electrical characterizations of the prepared sensors are carried out by XRD Rietveld structure refinement analyses, SEM, AFM, UV-VIS spectrophotometer, and source meter. By controlling the deposition temperture of 400 degrees C, a co-existing phase of MoO3 and MoO2 in WO3 matrix is presented with high oxygen vacancies concentration as calculated from the XRD Rietveld Refinement analyses. By increasing the Mo content, the calculated oxygen vacancies concentration increases by factor of 1.36. The optical characterization of Mo0.2W0.6O3 thin film shows a high transparent of 99.6% at 500 nm. The prepared thin films have successfully tested to detect carbon dioxide (CO2) at RT (20 degrees C) with high selectivity and repeatability. The Mo0.4W0.6O3 sensor film shows an electrical Schottky contact with fast response and recovery times towards CO2 under UV light activation. Mo0.4W0.6O3 thin film under dark and UV conditions were able to detect low CO2 concentration of 2 and 0.5 sccm CO2 M RT, respectively. Under UV illumination, Mo0.4W0.6O3 film shows a fast response and recovery time of 6.53 and 8.05 sat 0.5 sccm with sensitivity of 29.19%. Under UV photonic activation, higher electron concentration is presented in the oxide surface, which leads to high probability for reaction with CO2 molecules, and consequently enhanced the chemisorption of CO2. The enhanced CO2 gas sensitivity and fast response may refer to the high oxygen vacancies concentration and the active role of the grain boundaries in MoO2, MoO3 and WO3 mixed-valence nanostructured under UV activation.Öğe Functionality and Activity of Sol-Gel-Prepared Co and Fe co-Doped Lead-Free BTO for Thermo-Optical Applications(Amer Chemical Soc, 2023) Tihtih, Mohammed; Ibrahim, Jamal Eldin F. M.; Basyooni, Mohamed A.; En-nadir, Redouane; Hussainova, Irina; Kocserha, IstvanThe BTO, BFTC, and BCTF compounds were synthesized by the sol- gel method. The XRD study revealed the formation of single-phase tetragonal perovskite structures with the space group (P4mm). The crystalline parameters were studied as a function of Fe and Co contents and occupation of Ba and/or Ti sites by Fe and Co in the BTO lattice. It was found that the obtained strain increases when Ba2+ is substituted by Co2+ and Ti4+ by Fe3+. The Raman investigation confirmed the existence of three active modes (B1/E (TO1LO), (E (TO)/A1(TO3), and (A 1(LO)/E (TO), all of which are related to the existence of the tetragonal phase and strongly support the XRD results. The microstructural study showed a clear correlation between the presence of Fe and Co and the grain size distribution. Optical studies revealed the improvement in band gap energy with transition-metal (Fe and Co) co-doped BTO ceramics. The decrease in the band gap is explained by the competing effects of Columbian interactions, microdeformation, and oxygen defects. The results indicate that the presence of Fe and Co dopants enhances the absorption in the BTO ceramic. The dopants demonstrated an effect on thermal conductivity: they decreased the thermal conductivity of BTO, which is in the range of 0.76-2.23 W m(-1) K-1 at room temperature and 2.02-0.27 W m(-1) K-1 at elevated temperatures. The microstructure of the manufactured materials and the grain size distribution affect the compressive strength.Öğe High-Performance Negative Self-Powered ?-MoO3/Ir/?-MoO3 Photodetectors: Probing the Influence of Coulomb Deep Traps(Amer Chemical Soc, 2023) Basyooni, Mohamed A.; Tihtih, Mohammed; Zaki, Shrouk E.; Eker, Yasin RamazanNanostructures of ultrathin 2D MoO3 semiconductors have gained significant attention in the field of transparent optoelectronics and nanophotonics due to their exceptional responsiveness. In this study, we investigate self-powered alpha-MoO3/Ir/alpha-MoO3 photodetectors, focusing on the influence of induced hot electrons in ultrathin alpha-MoO3 when combined with an ultrathin Ir plasmonic layer. Our results reveal the presence of both positive and negative photoconductivity at a 0 V bias voltage. Notably, by integrating a 2 nm Ir layer between post-annealed alpha-MoO3 films, we achieve remarkable performance metrics, including a high I-ON/I-OFF ratio of 3.8 x 10(6), external quantum efficiency of 132, and detectivity of 3.4 x 10(11) Jones at 0 V bias. Furthermore, the response time is impressively short, with only 0.2 ms, supported by an exceptionally low MoO3 surface roughness of 0.1 nm. The observed negative photoresponse is attributed to O-2 desorption from the MoO3 surface, resulting in increased carrier density and reduced mobility in the Ir layer due to Coulomb trapping and oxygen vacancy deep levels. Consequently, this leads to a decreased carrier mobility and diminished current in the heterostructure. Our findings underscore the enormous potential of ultrathin MoO3 semiconductors for high-performance negative conductivity optoelectronics and photonic applications.Öğe Impact of thickness on optoelectronic properties of ?-MoO3 film photodetectors: Integrating first-principles calculations with experimental analysis(Elsevier, 2023) Basyooni, Mohamed A.; Achehboune, Mohamed; Boukhoubza, Issam; Gaballah, A. E. H.; Tihtih, Mohammed; Belaid, Walid; En-nadir, RedouaneThis study focused on investigating the optoelectronic properties of molybdenum trioxide (alpha-MoO3) thin films using the atomic layer deposition (ALD) technique through different cycle numbers and theoretical investigation. Initial band gap calculations using standard DFT with GGA-PBE resulted in a value of 1.19 eV, which deviated significantly from experimental measurements. The GGA + U method with Hubbard U corrections was applied for the first time to improve the accuracy. This refinement led to a more precise band gap value of 3.09 eV, closely matching previously reported experimental data. The electronic parameters of the alpha-MoO3 photodetector, such as ideality factor (n), barrier height (phi 0), and series resistance (Rs), were analyzed using the thermionic emission theory and confirmed by Cheung and Nord's methods. The results demonstrated that the sample deposited with 100 pulses exhibited higher photodetector performance under UV illumination, despite having a lower Rs.Öğe Iridium/Silicon Ultrathin Film for Ultraviolet Photodetection: Harnessing Hot Plasmonic Effects(Wiley-V C H Verlag Gmbh, 2024) Basyooni, Mohamed A.; Tihtih, Mohammed; Boukhoubza, Issam; Ibrahim, Jamal Eldin F. M.; En-nadir, Redouane; Abdelbar, Ahmed M.; Rahmani, KhalidThe phenomenon of hot carriers, which are generated through the nonradiative decay of surface plasmons in ultrathin metallic films, offers an intriguing opportunity for subbandgap photodetection even at room temperature. These hot carriers possess sufficient energy to inject into the conduction band of a semiconductor material. The groundbreaking use of iridium (Ir) ultrathin film as an ultraviolet (UV) plasmonic material on silicon (Si) for high-performance photodetectors (PHDs) has been successfully demonstrated. Elevating the thickness of the sputtered Ir film to 4 nm yields a notable surge in photocurrent, registering an impressive 600 & mu;A under 365 nm UV illumination with electron mobility of 1.37E3 cm2 V-1 s. This PHD exhibits excellent OFF-ON photoresponses at various applied voltages ranging from 0 to 5 V, maintaining a stable photocurrent. Under UV illumination, it displays exceptional performance, achieving a high detectivity of 1.25E14 Jones and a responsivity of 1.28 A W-1. These outstanding results underscore the significant advantages of increasing the thickness of the Ir film in PHDs, leading to improvements in conductivity, detectivity, external quantum efficiency, responsivity, as well as superior sensitivity for light detection. Exploring hot plasmon effects in iridium/silicon ultrathin films: This study delves into a remarkable ultrasmooth iridium thin film's application in hot electron plasmonic photodetectors. Exciting strides in optoelectronic devices are anticipated, owing to their capability for efficient light modulation, absorption, and conversion, with implications for photodetection and solar energy transformation.image & COPY; 2023 WILEY-VCH GmbHÖğe Nanostructured MoS2 and WS2 Photoresponses under Gas Stimuli(Mdpi, 2022) Basyooni, Mohamed A.; Zaki, Shrouk E.; Alfryyan, Nada; Tihtih, Mohammed; Eker, Yasin Ramazan; Attia, Gamal F.; Yilmaz, MucahitThis study was on the optoelectronic properties of multilayered two-dimensional MoS2 and WS2 materials on a silicon substrate using sputtering physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques. For the first time, we report ultraviolet (UV) photoresponses under air, CO2, and O-2 environments at different flow rates. The electrical Hall effect measurement showed the existence of MoS2 (n-type)/Si (p-type) and WS2 (P-type)/Si (p-type) heterojunctions with a higher sheet carrier concentration of 5.50 x 10(5) cm(-2) for WS2 thin film. The IV electrical results revealed that WS2 is more reactive than MoS2 film under different gas stimuli. WS2 film showed high stability under different bias voltages, even at zero bias voltage, due to the noticeably good carrier mobility of 29.8 x 10(2) cm(2)/V. WS2 film indicated a fast rise/decay time of 0.23/0.21 s under air while a faster response of 0.190/0.10 s under a CO2 environment was observed. Additionally, the external quantum efficiency of WS2 revealed a remarkable enhancement in the CO2 environment of 1.62 x 10(8) compared to MoS2 film with 6.74 x 10(6). According to our findings, the presence of CO2 on the surface of WS2 improves such optoelectronic properties as photocurrent gain, photoresponsivity, external quantum efficiency, and detectivity. These results indicate potential applications of WS2 as a photodetector under gas stimuli for future optoelectronic applications.Öğe Observation of negative photoresponse in joule-heated Au/Cu2SnS3 ternary chalcogenide thin film deposited by low energy pulsed laser deposition(Elsevier, 2022) Basyooni, Mohamed A.; Belaid, Walid; Houimi, Amina; Zaki, Shrouk E.; Eker, Yasin Ramazan; Gezgin, Serap Yigit; Kilic, Hamdi SukurGold (Au) nanoparticles trapped within Cu2SnS3 (CTS) thin films were effectively deposited on a low-cost glass substrate using a simple pulsed laser deposition of 15 mJ for 5 ns at a 10 Hz repetition rate. The film's structural, morphological, topography, optical, and optoelectronic properties were investigated. Highly crystalline ternary chalcogenide CTS with tetragonal symmetry and 17 nm grain size is prepared. The 110 0 resistivity of the thin film increases up to 125 0 indicating a negative photoresponse under visible light excitation. The decrease in the photocurrent is also observed with Cu2SnS3/Au/Cu2SnS3 sandwich ternary chalcogenide structure at resistivities values from 31 to 35 0 and a Joule effect influence the presence of plasmonic Au nanoparticle interlayers involved a lower phonon disorder given a higher photoresponse effect as predicted from Urbach energy.Öğe Photonic bandgap engineering in (VO2) n /(WSe2) n photonic superlattice for versatile near- and mid-infrared phase transition applications(Iop Publishing Ltd, 2022) Basyooni, Mohamed A.; Zaki, Shrouk E.; Tihtih, Mohammed; Eker, Yasin Ramazan; Ates, SuleThe application of the photonic superlattice in advanced photonics has become a demanding field, especially for two-dimensional and strongly correlated oxides. Because it experiences an abrupt metal-insulator transition near ambient temperature, where the electrical resistivity varies by orders of magnitude, vanadium oxide (VO2) shows potential as a building block for infrared switching and sensing devices. We reported a first principle study of superlattice structures of VO2 as a strongly correlated phase transition material and tungsten diselenide (WSe2) as a two-dimensional transition metal dichalcogenide layer. Based on first-principles calculations, we exploit the effect of semiconductor monoclinic and metallic tetragonal state of VO2 with WSe2 in a photonic superlattices structure through the near and mid-infrared (NIR-MIR) thermochromic phase transition regions. By increasing the thickness of the VO2 layer, the photonic bandgap (PhB) gets red-shifted. We observed linear dependence of the PhB width on the VO2 thickness. For the monoclinic case of VO2, the number of the forbidden bands increase with the number of layers of WSe2. New forbidden gaps are preferred to appear at a slight angle of incidence, and the wider one can predominate at larger angles. We presented an efficient way to control the flow of the NIR-MIR in both summer and winter environments for phase transition and photonic thermochromic applications. This study's findings may help understand vanadium oxide's role in tunable photonic superlattice for infrared switchable devices and optical filters.Öğe Reduced graphene oxide-functionalized zinc oxide nanorods as promising nanocomposites for white light emitting diodes and reliable UV photodetection devices(Elsevier Science Sa, 2023) Boukhoubza, Issam; Derkaoui, Issam; Basyooni, Mohamed A.; Achehboune, Mohamed; Khenfouch, Mohammed; Belaid, Walid; Enculescu, MonicaWe present a breakthrough in the development of novel nanocomposites based on reduced graphene oxide (RGO)-functionalized zinc oxide (ZnO) nanorods that hold exceptional promise for their use in white light emitting diodes (LEDs) and reliable UV photodetection. The nanorods had a pristine hexagonal wurtzite struc-ture, as confirmed by XRD analysis. SEM images revealed sandwich-like nanocomposites with ZnO nanorods coated in reduced graphene oxide and embedded between two layers of RGO. The study also confirmed the hybridization and interactions between the layers using Raman measurements. The resulting nanocomposites displayed a lower band gap energy than ZnO and exhibited unique photoluminescence spectra with a white PL light. The photodetector based on RGO/ZnO/RGO sandwich structures demonstrated exceptional photoresponse, with higher photocurrent under UV illumination, making it highly promising for a wide range of optoelectronic applications. Overall, this study offers a novel and powerful approach to create nanocomposite structures with enhanced optical characteristics.Öğe Role of A-site (Sr), B-site (Y), and A, B sites (Sr, Y) substitution in lead-free BaTiO3 ceramic compounds: Structural, optical, microstructure, mechanical, and thermal conductivity properties(Elsevier, 2023) Tihtih, Mohammed; Ibrahim, Jamal Eldin F. M.; Basyooni, Mohamed A.; Kurovics, Emese; Belaid, Walid; Hussainova, Irina; Kocserha, IstvanStrontium and Yttrium-doped and co-doped BaTiO3 (BT) ceramics with the stoichiometric formulas BaTiO3, B1-xSrxTiO3, Ba1-xYxTiO3, BaTi1-xYxO3, Ba1-xYxTi1-xYxO3, and Ba1-xSrxTi1-xYxO3 (x = 0.075) noted as BT, BSrT, BYT, BTY, BYTY, and BSrTY have been synthesized through sol-gel method. X-ray diffraction (XRD) patterns of the prepared ceramics, calcined at a slightly low temperature (950 degrees C/3h), displayed that BT, BSrT, and BYT ceramics possess tetragonal structures and BTY, BYTY, and BSrTY have a cubic structure. The incorporation of the Ba and/or Ti sites by Sr2+ and Y3+ ions in the lattice of BaTiO3 ceramic and the behaviors of the crystalline characteristics in terms of the Y and Sr dopant were described in detail. The scanning electron microscopy (SEM) images demonstrated that the densification and grain size were strongly related to Sr and Y elements. UV-visible spectroscopy was used to study the optical behavior of the as-prepared ceramic samples and revealed that Sr and Y dopants reduce the optical band gap energy to 2.74 eV for the BSrTY compound. The outcomes also demonstrated that the levels of Urbach energy are indicative of the created disorder following the inclusion of Yttrium. The measurements of the thermal conductivity indicated the influence of the doping mechanism on the thermal conductivity results of the synthesized samples. Indeed, the thermal conductivity of BaTiO3 is decreased with Sr and Y dopants and found to be in the range of 085-2.23 W.m(-1). K-1 at room temperature and decreases slightly with increasing temperature from 2.02 to 0.73-W.m(-1). K-1. Moreover, the microstructure and grains distribution of the BT, BSrT, BYT, BTY, BYTY, and BSrTY samples impacted the compressive strength, hence; the compressive strength was minimized as the grain size decreased.Öğe Role of oxygen vacancies in vanadium oxide and oxygen functional groups in graphene oxide for room temperature CO2 gas sensors(Elsevier Science Sa, 2019) Zaki, Shrouk E.; Basyooni, Mohamed A.; Shaban, Mohamed; Rabia, Mohamed; Eker, Yasin Ramazan; Attia, Gamal F.; Yilmaz, MucahitThe greenhouse effect is involving global heating and climate change within the world. Carbon dioxide (CO2) is one of the major gas at the origin of this effect, but also the byproduct of human activity. Therefore, monitoring the indoor/outdoor CO2 emission by gas sensors is one of the priorities for environmental preservation. In this paper, the sensing performance of CO2 towards two different O-rich films have been studied; graphene oxide (GO) and vanadium dioxide (VO2). The preparation of GO film has been carried out by spray pyrolysis on fluorine tin oxide (FTO) prepared by the modified Hummers method. While the VO2 film has been sol-gel spin-coated on a glass substrate. Both films have been characterized using XRD, SEM and electrical properties. The CO2 gas sensing mechanism and the role of oxygen vacancies in VO2 are addressing. The oxygen functional groups in GO play a main role in the CO2 gas the sensitivity level and response time. Their gas sensing performances have been investigated based on measuring the response vs recovery time, dynamic response curve analysis and sensitivity. In order to better understand the sensing mechanism, characterization has been done with different gas concentrations. Both GO and VO2 based CO2-sensors are acted as an n-type sensor. Sensing behavior of GO at RT has explained to be mainly mediated by the oxygen functional groups and a wide range of active sites. In the other hand, VO2 contains oxygen vacancies and more defect sites which play a main role in the RT sensing activity and low recovery time. (C) 2019 Elsevier B.V. All rights reserved.Öğe Self-Powered UV Photodetector Utilizing Plasmonic Hot Carriers in 2D ?-MoO3/Ir/Si Schottky Heterojunction Devices(Wiley-V C H Verlag Gmbh, 2024) Basyooni, Mohamed A.; Zaki, Shrouk E.; Tihtih, Mohammed; Boukhoubza, Issam; En-nadir, Redouane; Derkaoui, Issam; Attia, Gamal F.Self-powered UV sensing has enormous potential in military and civilian applications. However, achieving high responsivity and fast response/recovery time presents significant challenges. Self-powered photodetectors (PDs) have several advantages over traditional PDs, including higher sensitivity, lower power consumption, and simpler design. This study introduces a breakthrough self-powered PD that uses a Schottky junction of 2D alpha-MoO3/iridium (Ir)/Si ultrathin film to detect 365 nm light at 0 V bias through using atomic layer deposition (ALD) and sputtering systems. The PD response is enhanced by plasmonic Ir-induced hot carriers, enabling detection in a mere 0.1 ms. Incorporating a 4 nm Ir layer boosts the responsivity from 0 to 34 A W-1, and the external quantum efficiency is elevated from 0 to 7E11 under 365 nm light illumination. It also has a high I-ON/I-OFF ratio of 11.22E4 at 0 V. These results make the MoO3/4 nm Ir/Si structure an interesting option for self-powered PDs with high efficiency, and the use of a simple ALD system for large-scale fabrication of 2D alpha-MoO3 on hot carrier Ir plasmonic layer. The findings of this research hold tremendous promise in the field of UV sensing and can lead to exciting developments in military and civilian technology.Öğe Structural, optical, and electronic properties of barium titanate: experiment characterisation and first-principles study(Taylor & Francis Ltd, 2022) Tihtih, Mohammed; Ibrahim, Jamal Eldin F. M.; Basyooni, Mohamed A.; Belaid, Walid; Gomze, Laszlo A.; Kocserha, IstvanTo study the structural, electronic, and optical properties of lead-free Barium titanate BaTiO3 (BT) ferroelectric material in its tetragonal structure, a combination of experimental and theoretical studies has been used and the obtained results were discussed. The studied BT compound was prepared via the sol-gel technique. The calculated bandgap energy (E-g) and structural parameters of BT are determined using four types of exchange-correlation functionals (PBE, PBEsol, LDA, and PW91) in the perspective of the density functional theory (DFT). XRD and Raman analysis have shown that BT ceramic exhibits a tetragonal phase structure without any trace of impurity phases. The UV-vis investigation showed that BT has a bandgap energy of 3.19 eV, which is larger than the theoretically calculated values. The computed lattice parameter c is overestimated (as large as similar to 1% deviation) when using the LDA approximation. In contrast, PBEsol proved that those lattice constants were close to the experimental values (a deviation of less than 1%).Öğe Structural, optical, electrical and room temperature gas sensing characterizations of spin coated multilayer cobalt-doped tin oxide thin films(Academic Press Ltd- Elsevier Science Ltd, 2020) Basyooni, Mohamed A.; Eker, Yasin Ramazan; Yilmaz, MucahitThe negative charge trapped in the oxygen species present in metal oxides like Tin Oxide (SnO2) caused an upward band bending and makes these materials as promising sensing materials for CO2 detection. However, sensors based on pure SnO2 may only detect CO2 at high temperature making them un-sensitive at room temperature (RT) (20 degrees C). In this study, SnO2 and Cobalt doped SnO2 (Co:SnO2) thin films of varying thickness were successfully synthesized by sol-gel spin coating technique, followed by annealing. The highly active surface due to high number of divided layers has been determined by X-ray diffraction (XRD) for neat and doped SnO2 deposition. Moreover, the effect of increasing the annealing from 400 to 500 degrees C has been evaluated. The calculated band gap of the multilayer sample annealed at 500 degrees C blue shifted from 3.55 to 3.81 eV with the Co doping. Therefore, the Co doped SnO2 can detect CO2 as low as 30 vol% in atmosphere at RT, meanwhile the un-doped SnO2 coating shows a weak response. Moreover, at high CO2 concentration the recovery time decreases due to the high desorption kinetic. The obtained results illustrate the control of the film's properties gives the opportunity to manage the sensing and optoelectronic performance.
