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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 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 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 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.
