Bilgin, V., Akyuz, I., Kose, S., & Atay, F. (2006). Characterization of Mn-incorporated CdO films grown by ultrasonic spray pyrolysis. Semiconductor science and technology, 21(5), 579.
Abstract- CdO films, belonging to the transparent conducting oxide family which has great application potential in photovoltaic solar cells, were deposited onto glass substrates at a substrate temperature of 300 ± 5 ◦C by an ultrasonic spray pyrolysis technique. The electrical, optical, structural and surface properties of all the deposited films were investigated, and the effect of Mn incorporation (at 2% and 4%) on some physical properties of the CdO films was presented. The films displayed good electrical conductivity and optical transmittance in the visible region of the spectrum. Structural, morphological and elemental analyses of the films were characterized using x-ray diffraction patterns, scanning electron microscopy and energy dispersive x-ray spectroscopy, respectively. The investigations showed that CdO and CdO:Mn films can be suitable materials for optoelectronic applications, especially as transparent contacts for photovoltaic solar cells.
Engin, M., Atay, F., Kose, S., Bilgin, V., & Akyuz, I. (2009). Growth and characterization of Zn-incorporated copper oxide films. Journal of electronic materials, 38(6), 787-796.
Abstract-In this work, undoped and Zn-doped copper oxide films were deposited on glass substrates at a substrate temperature of 250 ± 5°C by using an ultrasonic spray pyrolysis technique. Electrical, optical, and structural properties of the films were investigated, and the effect of Zn incorporation on these properties are presented. The variations of electrical conductivities and electrical conduction mechanisms of all films were investigated in the dark and in the light. Optical properties of the produced films were analyzed by transmission, linear absorption coefficient, and reflection spectra. The band gaps of the films were determined by an optical method. The film structures were studied by x-ray diffraction. To obtain information about structural properties in detail, the grain size (D), dislocation density (δ), and lattice parameters for preferential orientations were calculated. The elemental analyses were performed using energy-dispersive x-ray spectroscopy. It was concluded that Zn has a strong effect, especially on the electrical and structural properties, and the undoped and Zn-doped copper oxide (at 3%) films may be used as absorbing layers in solar cells due to their low resistivities and suitable linear absorption coefficient values.
Keywords: Copper oxide films ultrasonic spray pyrolysis electrical and optical properties XRD EDS
Kose, S., Atay, F., Bilgin, V., Akyuz, I., & Ketenci, E. (2010). Optical characterization and determination of carrier density of ultrasonically sprayed CdS: Cu films. Applied Surface Science, 256(13), 4299-4303.
Abstract-In this work, CdS and Cu doped CdS films (at the Cu percentages of 1, 3 and 5) have been deposited onto glass substrates at 350 ± 5 °C by ultrasonic spray pyrolysis technique and their application potential for photovoltaic solar cells have been investigated. Optical properties and thicknesses of the films have been investigated by spectroscopic ellipsometry (SE). Ellipsometric angle ψ was used as the source point for optical characterizations. The optical constants (n and k) and the thicknesses of the films have been fitted according to Cauchy model. Also, optical properties of the produced films have been analyzed by transmittance and reflectance spectra. Refractive index (n), extinction coefficient (k) and reflectance (R) spectra have been taken by spectroscopic ellipsometer, while transmittance spectra have been taken by UV/vis spectrophotometer. The optical method has been used to determine the band gap type and value of the films. Mott-Schottky (M-S) measurements have been made to determine the conductivity type and carrier concentration of the films. Samples showed n-type conductivity and carrier concentration of undoped CdS sample was found to be 1.19 × 1019 cm−3. Also, it was concluded that Cu doping has an acceptor effect in CdS samples. From the results of these investigations, the application potential of CdS:Cu films for photovoltaic solar cells as window layer was searched.
Keywords: Ultrasonic spray pyrolysis; CdS:Cu films; Spectroscopic ellipsometry; Optical characterization; Mott-Schottky measurements
Atay, F., Akyuz, I., Kose, S., Ketenci, E., & Bilgin, V. (2011). Optical, structural and surface characterization of CdO: Mg films. Journal of Materials Science: Materials in Electronics, 22(5), 492-498.
Abstract-In this work, we have tried to improve some physical properties of CdO films by Mg doping. Ultrasonic spray pyrolysis technique has been used to obtain the films. Thicknesses and refractive indices of the films have been determined by Spectroscopic ellipsometry technique using Cauchy-Urbach model for fitting. Transmission and reflectance spectra have been taken by UV Spectrophotometer, and band gap values have been determined by optical method. X-ray diffraction patterns have been used to study the structural properties. Texture coefficient, grain size and lattice constants have also been determined. AFM images have been taken to see the effect of Mg doping on surface topography and roughness of CdO films. Finally, it has been concluded that Mg doped CdO films (especially at 4%) have improved properties and are good candidates for photovoltaic applications.
Akyuz, I., Kose, S., Atay, F., & Bilgin, V. (2007). Some physical properties of chemically sprayed Zn1−xCdxS semiconductor films. Materials Science in Semiconductor Processing, 10(2), 103-111.
Abstract-The ZnS is a direct and wide band gap material and it is used in optoelectronics and especially in photovoltaic solar cell applications. We tried to improve some physical characteristics of ZnS films by Cd incorporation. In this work, Zn1−xCdxS semiconductor films were produced by ultrasonic spray pyrolysis (USP) technique. Zn1−xCdxS films were obtained with incorporation of Cd element into ZnS at different concentrations (0£x£1). The electrical, optical, structural and morphological properties were investigated. The current–voltage characteristics were taken to see the electrical conduction mechanism and to determine the electrical conductivities of the films. Optical band gaps of the films were determined by optical method and structural properties were analyzed using X-ray diffraction (XRD) patterns. Also, scanning electron microscope (SEM) images were taken to see the distribution on the surface and energy dispersive X-ray spectroscopy (EDS) was used for elemental analysis. It was seen that some Cd incorporated films have higher conductivity values and more homogeneous distributions on the surface than ZnS films. Also, crystallinity level of the films increased. Finally, we think that different experimental parameters and Cd incorporation will improve the properties of ZnS films to be used in optoelectronics and photovoltaic solar cells.
Keywords: ZnS:Cd films; Ultrasonic spray pyrolysis; Electrical, optical, structural and morphological properties
Sarica, E., & Bilgin, V. (2016). Structural, optical, electrical and magnetic studies of ultrasonically sprayed ZnO thin films doped with vanadium. Surface and Coatings Technology, 286, 1-8.
Abstract-Undoped 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 °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.
Keywords: Zinc oxide; V doped zinc oxide; Structural properties; Optical properties; Magnetic properties; Spray pyrolysis
Bilgin, V., Kose, S., Atay, F., & Akyuz, I. (2005). The effect of substrate temperature on the structural and some physical properties of ultrasonically sprayed CdS films. Materials Chemistry and Physics, 94(1), 103-108.
Abstract-In this work, cadmium sulfide (CdS) films were prepared by ultrasonic spray pyrolysis (USP) technique onto glass substrates at different temperatures ranging from 473 to 623 K in 50 K steps, using aqueous solution of cadmium chloride and thiourea salts. The structural, optical and electrical properties of the prepared films were analyzed by X-ray diffraction, absorbance spectra and current–voltage (I–V) characteristics, respectively. After all investigations, it was concluded that 573 K substrate temperature is suitable for producing CdS films with USP technique and the examined properties (good crystallinity and low resistivity) of this film show its feasibility for technological purposes, especially for solar cells.
Keywords: CdS films; Ultrasonic spray pyrolysis; Electrical; Optical; Structural properties
Demirselcuk, B., & Bilgin, V. (2013). Ultrasonically sprayed ZnO: Co thin films: Growth and characterization. Applied Surface Science, 273, 478-483.
Abstract-In this work, undoped and cobalt-doped ZnO thin films were deposited at 275 ± 5 °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 (0 0 2) 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.
Keywords: Zinc oxide; Co doped zinc oxide; Optical properties; Electrical conductivity; XRD; AFM