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Öğe Characterization of CdS films and CdS/Si heterojunctions prepared by ultrasonic spray pyrolysis and their response to light(Elsevier, 2020) Bilgin, Vildan; Sarica, Emrah; Demirselcuk, Barbaros; Erturk, KadirIn this work CdS thin films were deposited onto glass and p-Si substrates by ultrasonically spraying of precursor solutions prepared in molarity ranging from 0.025 M, to 0.1 M. Structural investigations revealed that all films have hexagonal structure and mean crystallite size was found to be in the range of 18 nm-21 nm. On the other hand, CdS films exhibited 65-70% optical transmittance and band gap energy for all films was found to be about 2.42 eV. Electrical measurements of CdS/Si heterojunctions were carried out under both dark and illumination conditions. Calculated ideality factor and zero-bias barrier height ranged from 3.02 to 2.66 and 0.74 eV-0.78 eV according to TE theory whereas they ranged from 6.91 to 4.73 and 0.71 eV-0.74 eV according to Cheungs' method. Increase in reverse saturation current when heterojunctions were illuminated indicated that they have good sensitivity to solar light.Öğe Effect of Pb:S molar ratio in precursor solution on the properties of lead sulphide thin films by ultrasonic spray pyrolysis(Elsevier Sci Ltd, 2017) Sarica, Emrah; Bilgin, VildanIn this work, PbS thin films were deposited onto glass substrate at 225 degrees C by spraying precursor solution prepared with different molar ratio of lead acetate and thiourea as a source of Pb2+ and S2- respectively in order to investigate the effect of Pb:S molar ratio in the precursor solution on the physical properties of PbS thin films. Structural investigations carried out by X-ray diffractometer have shown that all films have fcc cubic structure and the average crystal size increased from 11 nm to 25 nm with the increasing the thiourea ratio in the precursor solution. In order to analyze the surface morphology of PbS thin films, AFM and SEM images were taken and elemental analysis of the films was performed by EDS. Optical transmittance and absorption spectra show that all deposited films have fairly low transmittance and high absorbance in the visible region. Additionally, it was determined that optical band gap of the deposited films were varied between 1.18 eV and 1.37 eV. As a consequence of electrical investigations, it was seen that all films have p-type conductivity and electrical resistivity decreased by increasing thiourea molar ratio in the precursor solution. All examinations have revealed that the molar ratio of lead acetate and thiourea has a significant effect on the physical properties of PbS thin films.Öğe Fluorine-doped tin oxide films via ultrasonic spray pyrolysis: Investigation of physical properties post-annealing and their potential for TCO applications(Elsevier, 2024) Gunes, Ibrahim; Sarica, Emrah; Bilgin, Vildan; Kucukarslan, Ayse; Ozder, SerhatIn this study, undoped tin oxide (SnO2) and fluorine (F)-doped SnO2 (FTO) films at various doping levels were deposited on glass substrates using the ultrasonic spray pyrolysis technique, followed by an annealing process applied to the films after deposition. In line with this, the study reveals the significant impact of the fluorine doping level optimization on certain physical properties such as the structural, optical, and electrical characteristics of the obtained films, and presents the consequences of the variation in these physical properties for adaptability in various optoelectronic applications. No diffraction peaks were observed in the X-ray diffraction patterns of the deposited films. After the annealing process, however, films with a polycrystalline form and a rutile tetragonal crystal structure were obtained. It was observed that the crystallization levels were better in films doped with 5 % and 10 % F. The optical band gap values of the films were determined to vary between 3.35 eV and 3.68 eV. Furthermore, it was found that with the increase in F doping level, the resistivity (ranging from 2.1 Omega cm to 43.5 Omega cm) and sheet resistance (ranging from 1.62x10(5) Omega/sq to 35.9x10(5) Omega/sq) values of the films decreased, while the figure of merit values (ranging from 0.12x10(-8) Omega(-1) to 67.1x10(-8) Omega(-1)) increased. Among all FTO films, it was revealed that films doped with 10 % F exhibited the highest optical transmittance, the lowest electrical resistivity, and the highest figure of merit values.Öğe Improvement of structural, optical and magnetic properties of cobalt oxide thin films by doping with iron(Springer Science and Business Media Deutschland GmbH, 2021) Küçükarslan, Ayşe; Kuş, Esra; Sarıca, Emrah; Akyüz, İdris; Bilgin, Vildan; Demirselçuk, BarbarosIn this study, using the ultrasonic spray pyrolysis technique, undoped and Fe-doped (at 2, 4, 6%) Co3O4 films were deposited on microscope glass substrates at 300 ± 5 °C, and the effect of Fe doping on some physical properties of Co3O4 films was examined. The structural, optical, magnetic and morphological properties of all films were analyzed using X-ray diffractometer, UV–Vis spectrophotometer, vibrating sample magnetometer and atomic force microscope, respectively. Band gap values of Co3O4:Fe films were found to be between 1.98 and 2.12 eV with an additional sub-band corresponding to energies varying between 1.48 and 1.50 eV for all samples. Structural analysis showed that crystallization levels of the films were improved with the Fe doping. Also, hysteresis curves of the films showed weak ferromagnetic characteristics and the magnetic behavior of the films was found to be sensitive to doping amount of Fe. It was found that Fe doping has beneficial effect on some physical properties of Co3O4 films.Öğe In doped CdO films: Electrical, optical, structural and surface properties(Pergamon-Elsevier Science Ltd, 2009) Kose, Salih; Atay, Ferhunde; Bilgin, Vildan; Akyuz, IdrisRecently, there has been a lot of work on the production and investigation of the physical properties of Transparent Conducting Oxide (TCO) materials which have common application area in photovoltaic solar cells and some optoelectronic devices. In this work, CdO film which is a material belongs to TCO family has been produced by Ultrasonic Spray Pyrolysis technique on microscope glass substrates at the substrate temperature of 250 +/- 5 degrees C. Electrical, optical, structural and surface properties of undoped and In doped (at 1.3 and 5%) CdO films and the effect of In doping percentage on the physical properties of CdO films have been investigated. It has been determined that electrical conductivity of CdO film is high and this value has been decreased by in doping. After the optical investigations, it has been observed that the transmittances of the films are about 30% and decreased dramatically by in doping. XRD investigations showed that, films have polycrystalline structure and good crystallinity levels. It has been found that in element hasn't got an important effect on the morphology of the films after the examination of surface micrographs. It has been determined that Cd and O elements are present in the solid film by using EDS. After all investigations, it has been concluded that In doping has an important effect on the electrical, optical, structural and surface properties of CdO films. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.Öğe Iron doped ZnO thin films deposited by ultrasonic spray pyrolysis: structural, morphological, optical, electrical and magnetic investigations(Springer, 2018) Bilgin, Vildan; Sarica, Emrah; Demirselcuk, Barbaros; Turkyilmaz, SerenIn this work, undoped and Fe-doped ZnO thin films at various concentrations (2, 4 and 6 at.%) were deposited onto glass substrate by using ultrasonic spray pyrolysis in order to investigate the effect of Fe doping on the structural, morphological, optical, electrical and magnetic properties of ZnO thin films. X-ray diffractometer (XRD) results revealed that all deposited thin films have hexagonal wurtzite structure and Fe doping led to decrease in mean crystallite size. Atomic force microscopy images showed that thin films were composed of tightly packed grains. Optical examinations indicated that optical transmittance remarkably decreased with the increase in the amount of Fe concentration in thin films. Additionally, optical band gap of deposited films were determined in the range of 3.26-3.29 eV. It was determined that all deposited thin films have n-type conductivity and electrical resistivity increased up to 253.6 Omega cm as a consequence of Fe doping. Vibrating sample magnetometer measurements showed that all films have ferromagnetic behavior.Öğe Non-stoichiometric effect and disorder in as-prepared Cu2ZnSnS4 films deposited at different temperatures by ultrasonic spray pyrolysis(Elsevier Sci Ltd, 2022) Gunes, Ibrahim; Bilgin, Vildan; Sarica, EmrahA better understanding of its crystal structure, the formation of possible secondary phases, defects and Cu-Zn disorder effects is needed to improve the photovoltaic device performance of CZTS films. In this direction, the effect of deposition temperature on the structural inhomogeneities, such as secondary phases and Cu-Zn dis-order, etc. as well as opto-electrical properties of CZTS were experimentally examined. For this purpose, a non-stoichiometric spraying solution was prepared and ultrasonically sprayed onto glass substrates at different deposition temperatures (350 degrees C, 400 degrees C, 450 degrees C, and 500 degrees C) to obtain CZTS films. Afterward, the structural, morphological, elemental, optical, and electrical properties of the deposited films were investigated in detail. By Lorentzian deconvolution of Raman spectra, 14 Raman vibrational modes were detected and seven of these were assigned to the secondary phases. Also, the ordered-kesterite phase (337 cm-1) of CZTS was found to crystallize along with the disordered-kesterite phase (329 cm-1) due to the disorder of the cation (Cu-Zn) sublattice. Optical band gaps for CZTS films decreased from 1.89 eV to 1.42 eV with increasing in deposition temperature. It was seen that not only optical band gaps but also Cu-Zn disorder and the amount of secondary phases in CZTS films tightly depend on the deposition temperature.Öğe Optimization of chemically sprayed ZnS films by Mn doping(Elsevier, 2021) Demirselçuk, Barbaros; Kuş, Esra; Küçükarslan, Ayşe; Sarıca, Emrah; Akyüz, İdris; Bilgin, VildanIn this study, undoped and Mn doped ZnS films were grown on microscope glass substrates at substrate tem- perature of 400 ± 5 ◦C by using a low cost Ultrasonic Spray Pyrolysis technique, and the effect of Mn doping on some physical properties of ZnS films was investigated. Structural, optical, electrical and morphological prop- erties of all films were analyzed using X-ray diffractometer (XRD), UV–Vis spectrophotometer, two-probe technique and atomic force microscope (AFM), respectively. X-ray diffraction studies showed that all films were formed in ZnS hexagonal structure and the crystallization levels of the films were relatively improved due to the increase in the Mn doping ratio, especially for 4% doped films. It was determined that the average transmittance value of undoped ZnS film in the visible region is 38% and this value increases to 60% for the sample doped by Mn at the highest rate (12%). The band gap values of the films were calculated using the Tauc equation and determined to be between 3.82 and 3.94 eV. Electrical resistivity values of the films decreased significantly due to the Mn doping. Mn doping also caused ZnS films to have uniform surface morphologies consisting of noticeable particle formations. Figure of merit calculations showed that Mn doping has a favorable effect on ZnS films and ZnS:Mn (12%) films may be promising materials for applications such as photovoltaic solar cells and optoelectronic devices.Öğe Phase transition of ultrasonically sprayed VOx thin films: The role of substrate temperature(Elsevier GmbH, 2021) Sarıca, Emrah; Bilgin, Vildan; Akyüz, İdrisIn this study, vanadium oxide (VOx) semiconductor films were deposited on glass substrates using ultrasonic spray pyrolysis technique. The effect of the substrate temperature on the physical properties of the deposited thin films was investigated. For this purpose, 0.05 M VCl3 aqueous solutions were prepared and sprayed on glass substrates at different temperature of 225 °C, 275 °C, 325 °C and 375 °C. Structural properties of VOx thin films were investigated by taking x-ray diffraction (XRD) patterns and it was determined that the films deposited at 225 °C and 275 °C have tetragonal V4O9 phase while the ones deposited at 325 °C and 375 °C have mixture of α-V2O5 and β-V2O5, α-V2O5 being dominant. The optical band gap energies of the films were determined to be in the range of 2.29 eV to 2.42 eV. Electrical investigations revealed that VOx films have n-type conductivity and electrical resistivity decreased from 4.07 Ωcm to 0.67 Ωcm depending on the increase in substrate temperature. Scanning electron microscopy (SEM) images showed that morphology of the films highly is sensitive to substrate temperature.Öğe Preparation and Characterization of Ultrasonically Sprayed Zinc Oxide Thin Films Doped with Lithium(Springer, 2009) Bilgin, VildanZinc oxide thin films doped with Li were deposited by ultrasonic spray pyrolysis (USP) at 350 +/- A 5A degrees C on glass substrates from solutions of zinc acetate [Zn(CH3COO)(2) center dot A 2H(2)O] and lithium acetate [C2H3LiO2 center dot A 2H(2)O], in which the Li/Li + Zn ratios were 1 at.%, 3 at.%, and 5 at.%. The effects of the doping on the structural, optical, electrical, and morphological properties of the films were examined. X-ray diffraction patterns indicated that the undoped and Li-doped ZnO films had a polycrystalline hexagonal wurtzite structure with a (002) preferred orientation. The films showed optical transmission around 60-80% in the visible region of the spectrum. The films were found to be transparent in the wavelength range of 450-900 nm, with sharp ultraviolet absorption edges in the wavelength range of 350-450 nm. The absorption edge analysis revealed that the optical band gap energies for the films were between 3.24 eV and 3.29 eV, and the electronic transition was of the direct transition type. The width of the band tail states, which is connected to the localized states in the band gap, was estimated to be 82-113 meV by Urbach tail analysis. For study of the electrical properties of the films, Hall effect measurements, electrical conductivities, conductivity activation, and trap energies were investigated. The electrical measurements of the films were obtained in the dark, in vacuum, and in the temperature range of 10-300 K. Morphological studies for the films were carried out by scanning electron microscopy.Öğe Sol-gel derived ZnO:Sn thin films and fabrication of n-ZnO:Sn/p-Si heterostructure(Elsevier B.V., 2021) Sarıca, Emrah; Güneş, İbrahim; Akyüz, İdris; Bilgin, Vildan; Ertürk, KadirIn this work ZnO:Sn thin films were deposited onto glass and p-Si substrates by spin coating of prepared sols which contains different amounts of Zn(CH3COO)2·2H2O and SnCl2 (0, 5, 10 and 15%). Physical properties of ZnO films were examined as a function of SnCl2 in prepared sols. In addition to that, heterostructure examinations were also carried out by depositing all films on p-Si substrates as well. XRD studies revealed that all films have c-axis orientation with crystallite sizes between 38 and 47 nm. AFM and SEM images showed that morphology of the films remarkably deteriorated with the increase in amount of SnCl2 in sol. Optical transmittance and absorbance spectra showed that films have high transmittance and low absorbance in the visible region. Besides, optical band gap increased from 3.27 eV to 3.37 eV. Additional band gap energies were determined for 10% and 15% Sn doped ZnO films. Room temperature photoluminescence spectra for all films were deconvoluted for the evaluation of all emission bands and it was noted that incorporation of SnCl2 into sol led to enhancement of UV-blue emission bands and caused emission bands related to oxygen vacancies to diminish. Four-point-probe measurements revealed that electrical resistivity of ZnO:Sn films increased from 3.20 × 100 Ωcm to 2.82 × 104 Ωcm and diode ideality factor of Ag/ZnO:Sn/p-Si/Au heterostructure was calculated to be in the range of 2.14–4.59 while zero-bias barrier height is in the range of 0.63–0.78 eV.Öğe Structural, optical, electrical and magnetic studies of ultrasonically sprayed ZnO thin films doped with vanadium(Elsevier Science Sa, 2016) Sarica, Emrah; Bilgin, VildanUndoped and vanadium (V) doped (3, 6, 9 and 12 mol%) ZnO thin films were deposited onto glass substrates at the substrate temperature of 400 +/- 5 degrees C by ultrasonic spray pyrolysis technique. Depending on the doping concentration, the variation in the structural, morphological, elemental analysis, and optical, electrical and magnetic properties were investigated by means of X-ray diffractometer (XRD), atomic force microscope (AFM) and scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS), UV-vis spectrophotometer, current-voltage (I-V) measurements and vibrating sample magnetometer (VSM), respectively. The X-ray diffraction studies have revealed that all the films were polycrystalline with hexagonal wurtzite crystal structure. The transmittance in the visible region varied between 55 and 75% and it was observed that transmittance of deposited films decreased after incorporation of vanadium. The electrical resistivity studies for all the films were carried out by using the two-probe method and it was seen that the electrical resistivity of the ZnO films decreased sharply as a consequence of V doping. The VSM measurements showed that all deposited films have intrinsic ferromagnetic behavior at room temperature and it was also found that the ferromagnetic behavior of all the films was obviously affected by doping with vanadium. (C) 2015 Elsevier B.V. All rights reserved.Öğe Study of some physical properties of ultrasonically spray deposited silver doped lead sulphide thin films(Elsevier Sci Ltd, 2017) Sarica, Emrah; Bilgin, VildanIn this study, undoped and Ag doped PbS thin films at different concentrations were deposited onto glass substrates at 225 degrees C by using ultrasonic spray pyrolysis technique, in order to investigate the effect of Ag doping on the physical properties of PbS thin films. Structural investigations revealed that all doped PbS: Ag thin films have cubic structure and Ag doping enhances crystalline level of PbS thin films. It was determined that average crystallite size of PbS: Ag thin films increased from 24 nm to 49 nm by increasing Ag doping concentration. Morphological studies showed that surfaces of the films become denser after Ag doping. Optical transmittance and absorption spectra revealed that all deposited thin films have low transmission and high absorbance within the visible region and band gap energy of the PbS:Ag thin films were determined to be in the range of 1.37 eV and 1.28 eV by means of optical method. Electrical conductivity type of PbS: Ag films was determined to be p-type and calculated electrical resistivity was found to be lowest for Ag-doped PbS thin films at 2%.Öğe The Effect of Fe and Co doping on the Physical Properties of CdO Films Deposited by Ultrasonic Spray Pyrolysis(Springer, 2025) Demirselcuk, Barbaros; Gunes, Ibrahim; Sarica, Emrah; Kus, Esra; Kucukarslan, Ayse; Bilgin, VildanIn this study, Cadmium Oxide (CdO) semiconductor films with different iron (Fe) and cobalt (Co) concentrations have been produced at 350 degrees C substrate temperature on the glass substrates by the ultrasonic spray pyrolysis method. In the first part of this study, the Fe element was doped in different ratios (2, 4, 6%) to CdO films, and the films were characterized. At the end of this stage, the optimum Fe doping ratio was determined for CdO films. In the second step, CdO films were dually doped with Fe + Co. The electrical resistivities of CdO:Fe films were determined using a four-probe technique to measure their conductivities, carrier concentrations, mobilities, and electrical conductivity types through Hall measurements. The produced films showed n-type electrical conductivity. It was determined that with increasing doping ratios, the electrical resistivity generally increased, and the films exhibited n-type conductivity. The XRD patterns revealed that the crystal structures of the films were polycrystalline and cubic in structure. The lections of (111), (200), (220), (311), and (222) planes were observed in the XRD patterns. Upon examination of the SEM images, it was observed that the films had nearly homogeneous surfaces and good adhesion to the substrate. By utilizing the fundamental absorption spectra of the films, it was determined that they exhibited direct bandgap transitions, and the bandgap energy values ranged from 2.34 to 2.65 eV. In the structural analysis, all films were found to have a polycrystalline structure and cubic CdO crystal system. When the SEM images of CdO:(Fe + Co) films were examined, it was observed that the films had almost homogeneous surfaces. Based on all these analyses, it was concluded that the doping elements Fe and Co significantly influenced the physical properties of CdO thin films.Öğe Ultrasonically sprayed cobalt oxide thin films: Enhancing of some physical properties by nickel doping(Elsevier B.V., 2021) Kuş, Esra; Küçükkarslan, Ayşe; Demirselçuk, Barbaros; Sarıca, Emrah; Akyüz, İdris; Bilgin, VildanIn this study, the effect of Ni doping (3, 6, 9 at%) on structural, optical, electrical and magnetic properties of Co3O4 films was reported. Films were grown at 300 ± 5 °C substrate temperature via ultrasonic spray pyrolysis (USP) technique. The structural analyses showed that undoped and Ni (3%) doped films exhibit an amorphous structure. Ni doping at higher ratios caused the films to have improved crystallinity. Optical band gap values the films were found to be between 2.03 and 2.08 eV with an additional sub-band corresponding to energies varying between 1.35 and 1.46 eV. The electrical conductivity values of the films increased significantly depending on the Ni doping. The hysteresis curves of the films showed that the films have weak ferromagnetic properties. Ni doping significantly improved the structural and electrical properties of Co3O4 films making them suitable materials for technological applications.Öğe Ultrasonically sprayed ZnO:Co thin films: Growth and characterization(Elsevier Science Bv, 2013) Demirselcuk, Barbaros; Bilgin, VildanIn this work, undoped and cobalt-doped ZnO thin films were deposited at 275 +/- 5 degrees C on glass substrates by the ultrasonic spray pyrolysis technique. The structural, electrical, optical and surface characterization of the films as a function of the cobalt concentration in the spraying solution were studied by means of x-ray diffractometer, current-voltage characteristics, UV-vis spectrophotometer and atomic force microscope, respectively. X-ray diffraction reveals that the films are polycrystalline in nature with preferred orientations of (002) for the ZnO: Co (0, 2, 4 at.%) and (1 0 0) for the ZnO: Co (6 at.%). The optical transmittance of all films was studied as a function of wavelength in the range of 300-1100 nm. They exhibit high transparency in the visible wavelength region with some interference fringes and sharp ultraviolet absorption edges. The optical band gap and Urbach energy values of the films were found in the range of 3.250-3.301 eV and 90-230 meV, respectively. The electrical studies for all films were carried out by using conductivity-temperature measurements and it was seen that the electrical conductivity of ZnO films decreases slightly depending on the increasing of Co doping. Also, Co doping increases both energies of donor-like traps and activation energy for ZnO films. The surface morphology was analyzed by atomic force microscope and a strong dependence on the cobalt incorporation was found. (C) 2013 Elsevier B.V. All rights reserved.Öğe Ultrasonik kimyasal püskürtme tekniği ile hazırlanan n-CdS:Al/p-Si hetero-eklemini yapısal, optiksel ve elektriksel özellikleri(2012) Bilgin, Vildan; Demirselçuk, Barbaros; Ertürk, Kadir; Sarıca, Emrah[Abstract Not Available]
