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Öğe A study of the electronic and physical properties of SnO2 thin films as a function of substrate temperature(Elsevier Sci Ltd, 2019) Erken, O.; Ozkendir, O. M.; Gunes, M.; Harputlu, E.; Ulutas, C.; Gumus, C.In this work, tin dioxide (SnO2) thin films were prepared at various substrate temperatures (380-440 degrees C, in steps of 20 degrees C) on glass substrates by the Spray Pyrolysis Method. X-ray Diffraction (XRD) measurements revealed that the SnO2 thin films were formed in a tetragonal crystallized structure. The electronic structure of the tin dioxide thin films that were prepared at several substrate temperatures were investigated with the collected X-ray Absorption Spectroscopy (XAS) data. The crystal structure analysis was also supported by the Extended X-ray Absorption Fine Structure (EXAFS) data analysis extracted from the X-ray Absorption Fine Structure (XAFS) data. Unstable crystal behaviors were detected in the samples due to metastable SnO structure formations as a result of phase transitions from the SnO to SnO2 structure during the annealing processes. Clear information on the atomic displacements in the samples as a picture of the crystal mechanism was obtained from the analysis of EXAFS data. The SnO2 thin films were found to exhibit high transmittance (average 90%) in the 400-1100 nm interval. The thickness of the SnO2 thin film (t) and refractive index (n) were calculated from transmittance spectra in the visible region using envelope method. The direct energy band gaps of the films obtained were 4.01-4.09 eV. Atomic force microscope (AFM) measurements were performed in order to investigate the surface roughness of the SnO2 thin films.Öğe Effect of molar concentration on the structural, linear and nonlinear optical properties of CuS (covellite) thin films(Elsevier Ltd, 2022) Habiboglu, C.; Erken, O.; Gunes, M.; Yilmaz, O.; Cevlik, H.C.; Ulutas, C.; Gumus, C.CuS thin films with various molar concentrations at 70 °C temperature were deposited by Chemical Bath Deposition. The effect of molar concentration on the structural, linear optic, nonlinear optic and morphological properties of CuS films were deeply investigated. X-ray diffraction (XRD) analysis exhibited that CuS films were formed in polycrystal structure and hexagonal phase. The fundamental optical parameters of films such as energy band gap, reflection and extinction coefficient were determined with the results of optical transmission and optical absorption by UV–vis spectrophotometer. The energy band gap values were reduced with increasing films thickness. Moreover, the dependence of the optical dielectric constants, loss tangent, optical conductivity, surface and volume energy loss function values on the molar concentrations were studied. Furthermore, the third order nonlinear optical susceptibility and nonlinear refractive index, which is considered to be the base of the first order optical susceptibility with nonlinear optical properties were discussed in detail. © 2022 Elsevier LtdÖğe Influence of post-deposition annealing on the structural and optical properties of ?-MnS thin film(Elsevier Gmbh, 2018) Ulutas, C.; Gunes, M.; Gumus, C.gamma-MnS thin film was deposited at 40 degrees C temperature on glass substrate by Chemical Bath Deposition (CBD) method that has superior advantageous in terms of fast and cheap production. MnS thin film was annealed in nitrogen atmosphere at temperatures 100, 200, 300, 400, 500 C for an hour. The effect of annealing temperature on structural and optical properties have been investigated. X-ray diffraction (XRD) analysis revealed that gamma-MnS thin film had the phase change and oxidized at 400,500 C annealing temperature. The grain size of the annealed film was calculated between 241 and 280 angstrom as a function of annealing temperature. It was observed that optical transmission values decreased at wavelength of 400-700 nm (visible region) after annealing at temperatures 400 and 500 degrees C. Increasing annealing temperature induces reduction in energy band gap values from 3.89 eV down to 3.46 eV. Refractive index (n) values were calculated by envelope method: Refractive index values at visible region increased from 2.03 to 2.54 with increasing annealing temperature. (C) 2018 Elsevier GmbH. All rights reserved.Öğe Investigation on the electronic and physical properties of gamma-MnS films as a function of thickness(Elsevier Sci Ltd, 2022) Ulutas, C.; Erken, O.; Gunes, M.; Ozkendir, O. M.; Gumus, C.In this study, gamma-manganese sulphide (gamma-MnS) films were prepared at various thickness and deposition time at a temperature of 50 degrees C by Chemical Bath Deposition Method (CBD). The characterization of the gamma-MnS films were determined by using the following methods; X-ray Absorption Fine Structure Spectroscopy (XAFS), Xray diffraction (XRD), optical absorption, Field Emission-Scanning Electron Microscope (FE-SEM), Energy Dispersive X-ray analysis (EDX). The electronic interplay via the coupling between Mn 3d levels and S 2p levels was determined to build up strong molecular bonds containing broad band with hybrid pd levels at low energy levels. The results of the electronic structure analysis were also tested with the absorption spectroscopy calculations and high agreement is reported. XRD analysis revealed that the film deposited for 5 h had amorphous structure and turned to be crystal structure in hexagonal phase with deposition time 10, 15, 20 h due to increasing film thickness value. The optical band gap values were reduced from 3.86 eV to 3.10 eV with increasing film thickness. The average refractive index value of films at visible region were calculated between 1.55 and 2.81 as a function of increment in film thickness. The mobility and resistivity of the films were measured as 8.65-55.76 cm2/Vs and 3.10 x 105-2.39 x 106 omega cm, respectively, by Hall measurement.Öğe The effects of substrate on the physical properties of gamma-MnS thin films deposited by chemical bath deposition(Elsevier B.V., 2020) Ulutas, C.; Erken, O.; Gunes, M.; Gumus, C.Gamma-MnS thin films were deposited on glass and indium tin oxide (ITO) substrates at 40 °C temperature by Chemical Bath Deposition (CBD) method. XRD measurements revealed that the gamma-MnS films are polycrystalline in the wurtzite phases and show a preferential orientation along the c-axis. The grain size of the films that were deposited onto the glass and ITO were calculated as 327 nm and 189 nm, respectively. The energy band gap of the films deposited onto glass and ITO were also calculated as 3.56 eV, 3.74 eV, respectively. The refractive index of the gamma-MnS at the visible region (400–700 nm) were measured as 2.1 and 1.63 for the glass and ITO substrates, respectively. Hall measurement revealed that the gamma-MnS films showed n-type conductivity and the resistivity of the gamma-MnS films deposited on the glass and ITO substrates were measured as 7.1 × 105 ?cm, 3.04 × 102 ?cm, respectively. © 2020 Elsevier B.V.Öğe The influence of trisodium citrate dihydrate complexing agent on the structural, electrical and optical properties of ?-MnS thin films(Springer, 2023) Budak, Z.; Ulutas, C.; Yilmaz, O.; Cevlik, H. C.; Gunes, M.; Gumus, C.gamma-MnS films were prepared using trisodium citrate (TSC) complexing agents at different molarity values (0.5, 1 and 1.5 M). Characterization techniques such as X-ray Diffraction (XRD), optical absorption spectra, Field Emission-Scanning Electron Microscope (FE-SEM), Energy Dispersive X-ray (EDX) and Hall Effect were used to determine the properties of the films. As a result of XRD analysis, it was observed that the films prepared with 0.5 M TSC were formed in amorphous structure, while the films prepared with 1 M and 1.5 M TSC were formed in polycrystalline structure and hexagonal phase. In addition, it was determined that the crystallization of the films increased with the increase in the molarity of TSC. The optical gaps of the films were determined as 3.77 eV, 3.44 eV and 3.40 eV, respectively, depending on the increase in molarity of TSC. The refractive index values of the MnS films in the visible region (400-700 nm) were calculated as 1.87, 2.02 and 2.10, respectively. Electrical resistivity and mobility values from Hall Effect measurements were measured as 1.01 x 10(6), 9.68 x 10(5), 4.10 x 10(5) ohm cm and 33.01, 36.93, 56.53 cm(2)/Vs, respectively, depending on the increase in TSC molarity value.
