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Öğe Amplifying main physical characteristics of CuO films using ascorbic acid as the reducer and stabilizer agent(Springer Heidelberg, 2021) Akkaya, Abdullah; Kahveci, Osman; Aydin, Rasit; Sahin, BunyaminCopper oxide thin films have been grown by successive ionic layer adsorption and reaction technique, which is inexpensive, environmentally friendly and simple onto soda-lime glass substrates from an aqueous copper (II) chloride dehydrate solution with and without the addition of ascorbic acid (AA) at 70 degrees C. Surface morphology, crystalline structure, chemical compositions, optical and electrical properties of thin films were investigated with a focus on the influences of different concentrations of AA. The analysis exhibited that the main physical performances of the CuO films were found to change with AA content. Estimated crystallite sizes decreased from 24.64 to 12.78 nm with the addition of AA in the growth bath solutions. The optical bandgap energy of CuO is found to increase from 1.42 to 1.55 eV as a consequence of the increasing AA content. As the AA concentration in the solution bath increases the transmittance increases from approximate to 5 to approximate to 28%. FTIR transmittance spectra of CuO have a characteristic stretching vibration mode of the metal-oxide bonds and the addition of AA caused the appearance of many peaks of this molecule. Contact resistance values decreased with the AA content from 0.657 x 10(9) to 0.342 x 10(9) omega. It is worth noting that the deposition technique is low cost and very simple; obtained CuO thin films could be appropriate for different technological applications.Öğe Characteristics modification of ZnO/CuO composite films by doping rare-earth element Dy for real-time hydration level monitoring(Academic Press Ltd- Elsevier Science Ltd, 2022) Kirik, Nurdan Selin; Sahin, BunyaminIn this study, we focused on the efficacy and utility of nanostructured pristine and rare-earth (RE) element dysprosium (Dy) doped ZnO/CuO composite thin films in the implementation of real-time monitoring of sweat as a biological fluid. ZnO/CuO composite films were grown by using a simple and inexpensive SILAR method and their surface morphological, structural, and real-time monitoring of hydration level characteristics was investigated. The surface topographical and structural analyses showed that the primary physical characteristics of the ZnO/CuO nano -structures changed after the substitution of dysprosium. Sweat sensing response examinations presented encouraging sensing behavior at room condition. Hence, this research represents the development of low power sweat sensing material with improved sensor characteristics, which could be utilized in real-time hydration level monitoring, with advantage of simple and low-cost fabrication techniques.Öğe Comprehensive research on physical properties of Zn and M (M: Li, Na, K) double doped cadmium oxide (CdO) nanostructures using SILAR method(Elsevier Sci Ltd, 2017) Aydin, Rasit; Sahin, BunyaminThis research outlines the effect of Zn doping, (Zn+Li), (Zn+Na) and (Zn+K) doubly doping of nanostructured CdO films on the structural, morphological and optical properties of the films. Un-doped, Zn-doped, (Zn+Li), (Zn+Na) and (Zn+K) double doped CdO films were synthesized on soda lime glass substrates by the SILAR method. Manufactured CdO films attached well to the glass substrates, exhibited nano-sized structures, and the physical properties of the nanoparticles were modified by co-doping. The XRD analysis confirmed that all the films exhibited face-centered cubic structure with (111) and (200) preferential growth. Calculated crystallite size values of the CdO films via the Scherrer equation decreased with Zn doping and double-doping. Optical measurements revealed that doping modifies the band gap enabling the potential of these films to be utilized in optoelectronic applications.Öğe Double doping synergy to improve structural, morphological, optical, and electrical properties of solution-based Cd and M (M: Pb, Sn, Bi) double doped nanocrystalline copper oxide films(Springer Heidelberg, 2019) Sahin, Bunyamin; Aydin, RasitIn this study, nanostructured CuO, Cd0.01Cu0.99O and Cu0.98Cd0.01M0.01O (M: Pb, Bi, Sn) films were synthesized using the successive ionic layer adsorption and reaction technique. The effects of Cd-doping, Sn, Pb, and Bi double doping on the structural, morphological, optical, and electrical properties were systematically investigated via X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, and current-voltage (I-V) measurements, respectively. XRD results show that the peak intensity, crystallite size, and texture coefficient of the films changed intensely with double doping. SEM images reveal that the surface morphology of the nanostructures changed with the kind of dopant materials due to the differences in ionic radius. Energy dispersive X-ray spectroscopy studies confirmed the presence of Cd2+, Sn4+, Pb2+, and Bi+5 in the doped films. The estimated average optical band gap energies of the CuO samples varied from 1.366 to 1.480 eV with double doping. The lowest average electrical resistivity of 1.21 x 10(6) ohm cm was found for the Bi-0.01 Cd0.01Cu0.98O sample.Öğe Dual doping (Cu with rare-earth element Ce): An effective method to enhance the main physical properties of CdO films(Academic Press Ltd- Elsevier Science Ltd, 2019) Sahin, BunyaminY Pristine, Cu and Cu with Ce double-doped nanocrystalline CdO films were successfully synthesized by successive ionic layer adsorption and reaction method. The surface morphological characterization of nanostructured CdO samples was executed by scanning electron microscopy. It demonstrated that the type of doping alters the microstructure of thin films. The elemental analysis was performed via energy dispersive spectroscopy system. The structural properties of the CdO films were researched using X-ray diffraction which showed that the obtained films were with a cubic crystalline structure of CdO. Investigation of fourier transform infrared spectroscopy vibration spectra confirmed the property of the obtained samples. UV-Vis. examinations presented that the bandgap energy and transmittance values of the produced samples are increasing (about 32%) with increasing Ce-content. Variation in the conductivity of the pristine CdO films as a consequence of Cu-doping and Cu:Ce double-doping was investigated by 4-probe electrical resistivity measurement. It was observed that increasing double doping concentrations led to a systematic decrease in the conductivity.Öğe Effect of Cobalt Doping on Nanostructured CuO Thin Films(Springer, 2014) Bayansal, Fatih; Taskopru, Turan; Sahin, Bunyamin; Cetinkara, Haci AliThe growth of cobalt-doped nanostructured CuO thin films using the successive ionic layer adsorption and reaction (SILAR) method is presented. It is found that Co doping considerably influences the structural (X-ray diffraction (XRD)), morphological (finite-element-scanning electron microscopy (FESEM)), and optical (ultraviolet/visible (UV/vis.) and Raman) properties of the films. XRD experiments evidence that the crystallite size of the films decreased with increasing Co doping. FESEM images reveal that the grain size of the nanostructures decreased with increasing doping concentration. By UV/vis. analysis, it is found that Co doping has a decreasing effect on band gap energy. The broadening and downshift of the Raman peaks are mainly attributed to the quantum confinement effect of CuO nanostructures.Öğe Electrochemical amperometric biosensor applications of nanostructured metal oxides: a review(Iop Publishing Ltd, 2019) Sahin, Bunyamin; Kaya, TolgaBiological sensors have been extensively investigated during the last few decades. Among the diverse facets of biosensing research, nanostructured metal oxides (NMOs) offer a plethora of potential benefits. In this article, we provide a thorough review on the sensor applications of NMOs such as glucose, cholesterol, urea, and uric acid. A detailed analysis of the literature is presented with organized tables elaborating the fundamental characteristics of sensors including the sensitivity, limit of detection, detection range, and stability parameters such as duration, relative standard deviation, and retention. Further analysis was provided through an innovative way of displaying the sensitivity and linear range of sensors in figures. As the unique properties of NMOs offer potential applications to various research fields, we believe this review is both timely and provides a comprehensive analysis of the current state of NMO applications.Öğe Facile preparation and characterization of nanostructured ZnO/CuO composite thin film for sweat concentration sensing applications(Elsevier Sci Ltd, 2021) Sahin, Bunyamin; Kaya, TolgaThis research presents the morphological, structural, optical characterization and sweat sensing response of ZnO/CuO nanocomposite thin films synthesized by the SILAR (Successive Ionic Layer Adsorption and Reaction) method. The particle and crystallite size were increased with increasing SILAR cycles. AFM studies showed that the increase in the number of SILAR cycles resulted a decrease in surface roughness from 60 nm to 23 nm. The optical band energy and transmittance of the nanocomposite thin films were determined from the UV-Vis. spectrum as well as Tauc's plot, which showed a decrease in the optical band energy (from 2.06 to 1.89) with the increase of film thickness. Human hydration level sensing of the nanocomposite ZnO/CuO thin films was investigated by artificial sweat application. It was observed that there was a monotonous increase with the sensing response with respect to the artificial sweat concentration.Öğe A first-principle study of nanostructured CuO thin film-based caffeine sensing scheme(Elsevier Science Sa, 2021) Sahin, Bunyamin; Kaya, TolgaIn this study, we demonstrated the feasibility of nanostructured CuO thin film usage for caffeine sensing. Our morphological studies revealed that ellipse- or spiral-shaped nanostructured were formed with good crystal qualities. It was shown that the film thickness was decreased from 803 nm to 717 nm with an-nealing. Better crystalline quality of annealed films resulted in higher sensing response. Moreover, caffeine sensing response time was decreased to 19 s from 28 s for annealed films compared to as-grown CuO films. Both films exhibited excellent linearity with higher than 0.93 R-2 values for the caffeine values from 0.5 mM to 10 mM, which is the range for most caffeinated hot and cold beverages. Caffeine is considered the only legal stimulant and its excessive use is not healthy. Knowing the caffeine content of beverages using portable, cheap sensor devices will be beneficial for the health-conscious society. We believe our sensing scheme in using nanostructured semiconductor thin films will pave the way to ultimately create advanced materials-based portable sensor devices. (C) 2021 Elsevier B.V. All rights reserved.Öğe Green and cost-effective synthesis of zinc oxide thin films by L-ascorbic acid (AA) and their potential for electronics and antibacterial applications(Elsevier Sci Ltd, 2022) Tasdemir, Abdulkadir; Akman, Nazife; Akkaya, Abdullah; Aydin, Rasit; Sahin, BunyaminThe evolution of eco-friendly, green route and cheap technology for synthesizing nanostructured zinc oxide (ZnO) thin films using plant extracts is a promising choice because such materials present a widespread potential for numerous technological applications. This study proposes the green and cost-effective technique to synthesize stable ZnO thin films using a good reducing agent and facilitating many natural L-ascorbic acids (AA) metabolic reactions capacity. The influence of AA concentrations in the starting bath solution on ZnO samples' structural, morphological, electrical and antibacterial performances has been reported in detail. The main physical char-acteristics of the ZnO materials were improved by supplementing of reducing and capping agents AA. Average particle size varies with the adding AA from 58.29 to 48.68 nm and also thickness of these films was decreased from 0.82 to 0.44 mu m. Also, it was seen that, the presence of AA in the bath solution significantly affected the absorption process and causes a morphological alteration due to the reaction between Zn2+ and AA during the deposition process. FTIR transmittance spectra of bare ZnO presented that a transmittance peak about 886 cm(-1) and 748 cm(-1) was created by the characteristic stretching vibration mode of the Zn-O. The resistivity of the produced films significantly changed with AA concentration in the bath solution. Antibacterial potentials of bare ZnO and ascorbic acid added ZnO films were examined against economically important Staphylococcus aureus (ATCC 25923) gram-positive bacteria and Escherichia coli (ATCC 35218) gram-negative bacterial disease agents via handling paper disc diffusion assay. The obtained diameter of the zones of inhibition was 20.1 mm for E. coli and 28.1 mm for S. aureus at the dose of ZnO+AA 8.0%. These inhibition diameters were larger than the diameter of ampicillin as our positive control alone. This proves that the newly synthesized compound is a powerful antibacterial agent.Öğe Highly improved hydration level sensing properties of copper oxide films with sodium and potassium doping(Elsevier Science Bv, 2016) Sahin, Bunyamin; Kaya, TolgaIn this study, un-doped, Na-doped, and K-doped nanostructured CuO films were successfully synthesized by the successive ionic layer adsorption and reaction (SILAR) technique and then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and current-voltage (I-V) measurements. Structural properties of the CuO films were affected from doping. The XRD pattern indicates the formation of polycrystalline CuO films with no secondary phases. Furthermore, doping affected the crystal structure of the samples. The optimum conductivity values for both Na and K were obtained at 4 M% doping concentrations. The comparative hydration level sensing properties of the un-doped, Na-doped, and K doped CuO nanoparticles were also investigated. A significant enhancement in hydration level sensing properties was observed for both 4 M% Na and K-doped CuO films for all concentration levels. Detailed discussions were reported in the study regarding atomic radii, crystalline structure, and conductivity. (C) 2015 Elsevier B.V. All rights reserved.Öğe Investigation of Multi-Phase Structure and Optoelectronic Performance of Bi-Doped (Cu-Zn) Oxide Composite Thin Films(Wiley-V C H Verlag Gmbh, 2023) Altinay, Yasemin; Akkaya, Abdullah; Aydin, Rasit; Sahin, BunyaminIn this research, thin film composite structures were used to prepare optoelectronic devices from bare and Bi-substituted p-CuO/n-ZnO systems. The p-CuO/n-ZnO composite thin film structures were prepared by the SILAR technique, and the influences of two different Bi contents on the structure and main physical performances of the samples were investigated. The X-ray diffraction (XRD) technique showed that the composited thin film materials were multiphased in rutile hexagonal (wurtzite) phase (ZnO) and monoclinic tenorite phase (CuO) type crystal structure. The obtained surface morphological results presented that the structure exhibits an almost homogeneous, plate-like surface distribution, and depending on the increase of Bi concentration, the plate-like sheet area widens from similar to 2.5 mu m to 10 mu m and the layer boundaries decrease. FT-IR and Raman spectroscopy were used to investigate the various vibration and Raman active phonon modes of Bi:p-CuO/n-ZnO nanostructured heterostructures. For a comprehensive analysis of the optical bandgap of the fabricated composite samples, the estimated values were obtained from the Tauc plot. Produced samples exhibited an Ohmic behavior and dc resistivity values of films can be determined via Ohm's Law. The adjusted sheet resistance value of 11.51 M Omega/sq when the content of Bi 3.0 % in the growth bath.Öğe Mg-substituted ZnO/CuO composite films: A potential candidate for highly efficient human hydration level monitoring(Elsevier Science Sa, 2021) Coskun, Ezgi Asfuroglu; Sahin, BunyaminThis paper presents an attempt about hydration level monitoring of human sweat using nanostructured ZnO/CuO composite films. Nanostructured bare and alkaline earth metal magnesium (Mg) substituted ZnO/CuO composite films were synthesized by Successive Ionic Layer Adsorption and Reaction (SILAR) method and characterized by Field Emission Scanning Electron Microscopy, Atomic Force Microscopy, X-Ray Diffraction, Ultraviolet-Visible Spectroscopy and hydration level sensing measurements. The struc-tural and morphological analyses exhibited that the main physical properties of the ZnO/CuO composite samples were improved after substitution of magnesium. The ultraviolet-visible spectroscopy analysis presented that the band gap energy of ZnO/CuO films increased about 11 % with substitution of 2.0 % Mg in the ZnO/CuO structure. Sensing response analysis showed promising sensing behavior at room temperature. The Mg-substituted sample showed considerable sensing response for low concentration artificial sweat solution, with improved sensitivity at increased sweat concentration. Since the ZnO/CuO samples are responsive to the artificial sweat 131.00 mM solution (S = 3.12), sensitivity enhances to 9.26 for 2.0 % Mg substituted-ZnO/CuO sample. These enhanced properties were also demonstrated that Mg substituted-ZnO/CuO samples are good candidates to be employed for hydration level monitoring of human sweat. (c) 2021 Elsevier B.V. All rights reserved.Öğe A novel amperometric sweat sensor approach through characterization of Hausmannite (Mn3O4) thin films(Elsevier Sci Ltd, 2019) Sahin, Bunyamin; Aslan, Busra; Kaya, TolgaNanostructured metal oxides offer unique advantages for their sensing capabilities hence have been studied immensely. In the context of Mn3O4 films, this study focuses on the sweat sensing prospects of these advanced materials using SILAR method, for the first time. Mn3O4 films were successfully produced with varying thicknesses using SILAR method effectively. This repeatable process allowed these films to be tested in varying artificial sweat concentrations and it was found that Mn3O4 films are very responsive to varying sweat concentrations. Morphological, structural, and optical measurements showed the successful growth of Mn3O4 films with good uniformity, crystallinity, and smooth surface characteristics. Amperometric measurements with and without sweat concentrations showed that Mn3O4 films can indeed be used for sweat sensing applications.Öğe A novel approach to enhancement of surface properties of CdO films by using surfactant: dextrin(Taylor & Francis Ltd, 2015) Sahin, Bunyamin; Bayansal, Fatih; Yuksel, MustafaWe studied the effect of an organic surfactant, dextrin, concentration on structural, morphological and optical properties of nanostructured CdO films deposited on glass substrates by using an easy and low-cost SILAR method. Microstructures of the nanostructured CdO films were optimized by adjusting dextrin concentration. XRD, SEM and UV-Vis Spectroscopy were used to study phase structure, surface morphology and optical properties of CdO films. Furthermore, effects of dextrin concentration on the surface roughness characteristics of CdO samples were reported. The results showed that the presence of organic surfactant highly affected the physical properties of CdO nanomaterials.Öğe Physical Properties of Nanostructured CdO Films from Alkaline Baths Containing Saccharin as Additive(Hindawi Ltd, 2013) Sahin, BunyaminNanostructured cadmium oxide (CdO) films were fabricated on glass substrates from alkaline baths containing saccharin as an additive by a successive ionic layer adsorption and reaction (SILAR) method. The effects of saccharin concentration in the bath on the structural, morphological, and optical properties were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence, and Raman spectroscopy. The analyses showed that the surface morphologies, XRD peak intensities, Raman spectroscopy, and photoluminescence properties of CdO films changed with saccharin concentration. From the results, it can be said that morphological characteristic and optical properties of the films could be calibrated by adding various saccharin percentages in the growth bath.Öğe Preparation and Characterization of Zn x Cu(1-x)O Composite Films on Glass Substrates Through SILAR Processing(Springer, 2015) Bayansal, Fatih; Sahin, Bunyamin; Yuksel, MustafaCuO composite thin films with and without Zn-doping are deposited onto glass substrates by the SILAR method. All the films are characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), UV-Vis spectrophotometry, temperature dependent dc conductivity, and X-ray diffraction (XRD) measurements. SEM results show that the particle size decreases from 27 to 16 nm with increasing Zn-doping. EDX analysis evidences the amount of Zn in CuO films, which increases with increasing Zn concentration in the growth solutions. Transmittance, optical band gap, and activation energy values of the films are found to be increasing from the UV-Vis and temperature dependent dc conductivity measurements with increasing Zn-doping. It also is found from the XRD patterns that mean crystallite size of the films decreases from 18.94 to 13.70 nm with increasing Zn-doping. Moreover, increase in Zn concentration results peak shifts to lower 2 theta values. (C) The Minerals, Metals & Materials Society and ASM International 2015Öğe Real-time sweat analysis via alternating current conductivity of artificial and human sweat(Amer Inst Physics, 2015) Liu, Gengchen; Alomari, Mahmoud; Sahin, Bunyamin; Snelgrove, Samuel E.; Edwards, Jeffrey; Mellinger, Axel; Kaya, TolgaDehydration is one of the most profound physiological challenges that significantly affects athletes and soldiers if not detected early. Recently, a few groups have focused on dehydration detection using sweat as the main biomarker. Although there are some proposed devices, the electrical and chemical characteristics of sweat have yet to be incorporated into the validations. In this work, we have developed a simple test setup to analyze artificial sweat that is comprised the main components of human sweat. We provide theoretical and experimental details on the electrical and chemical behavior of the artificial sweat for various concentration values within a temperature range of 5 degrees C to 50 degrees C. We have also developed an efficient sweat collecting and detection system based on 3D printing. Human studies were conducted and this particular protocol has shown that dehydration starts to take effect as early as 40 min into the physical activity if there is no fluid intake during the exercise. We believe that our device will lead to developing viable real-time sweat analysis systems. (C) 2015 AIP Publishing LLC.Öğe The role of Triton X-100 as a surfactant on the CdO nanostructures grown by the SILAR method(Elsevier Science Sa, 2017) Aydin, Rasit; Sahin, BunyaminIn this work, the effect of surfactant Triton X-100 (TX-100) on structural, morphological and optical properties of nanostructured CdO films has been researched. Four series of nanostructured CdO films with TX-100 concentrations of 0.25e1.0 M% of the growth solution were prepared by the Successive Ionic Layer Adsorption and Reaction (SILAR) technique on glass substrates and were characterized by scanning electron microscopy, surface roughness, X-Ray diffraction and UV-Vis. Spectroscopy. Scanning electron microscopy exhibited that the particle thickness increased with increasing TX-100 content. Surface roughness (Ra) measurement exhibited that Ra value accordingly decreases in the presence of TX-100. From the X-Ray diffraction patterns it was calculated that the crystallite size of the films increased parallel to the particle size with increasing TX-100 content. UV results presented that the optical bandgap values of the film can be adjusted with TX-100 content where optical bandgap decreased with increasing TX-100 content in the growth bath. The results show that the amount of TX-100 in the growth bath played a significant mission in adjusting the main physical properties of the nanostructured CdO film. (C) 2017 Elsevier B. V. All rights reserved.Öğe Simple and low-cost synthesis of Al-doped ZnO/CuO composite nanowires for highly efficient hydration level sensing(Elsevier Sci Ltd, 2021) Sahin, Bunyamin; Acar, Aysegul; Kaya, TolgaIn this paper, we report on our investigation of the impact of Al doping on the primary physical properties of SILAR fabricated CuO/ZnO composite nanowires. Our characterization on surface and structural analysis showed that we were able to lightly dope the nanocomposites effectively using the SILAR method, which is cost-effective and repeatable. Conductivity of the Al-doped films changed significantly which resulted in greater sensing response for hydration. We utilized artificial sweat solutions to characterize the sensing response of the films and we demonstrated that sensing response almost doubled with Al doping. Transient response of sweat application also showed that response times were less than 10 s for 2% Al-doping. We conclude that Al doping on CuO/ZnO nanocomposites is an excellent candidate to be utilized for hydration sensing through sweat.
