Structural and surface studies of tin oxide films doped with fluorine (original) (raw)
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Electrical, structural and surface properties of fluorine doped tin oxide films
Applied Surface Science, 2010
Fluorine (F) incorporated polycrystalline SnO 2 films have been deposited onto glass substrates by ultrasonic spray pyrolysis technique. To possess information about the electrical properties of all films, their electrical conductivities were investigated depending on the temperature, and their activation and trap energies were analyzed. The crystalline structure, surface properties and elemental analysis of the SnO 2 films were examined to determine the effect of the F element. After all investigations, it was concluded that each fluorine incorporation rate has a different and important effect on the physical properties, and SnO 2 :F (3 at%) films were found to be the most promising sample for energy conversion devices, especially as conducting electrode in solar cells with its improved structural and electrical properties as compared to others.
Electrophoretic Deposition of Fluorine Doped Tin Oxide (F: SnO2) Films
Films of fluorine doped tin oxide (F:SnO2) particles were deposited using custom designed electrophoretic deposition set-up. The electrophoretic deposition of F:SnO2 particles was carried out over polished Al substrate with applied voltage of 60 V for 20 minutes. Surface profilometric studies have confirmed typical average film thickness of 10 m and an average roughness of 5μm. The thin-film was annealed at low temperature of 120 °C. XRD analysis confirmed phase purity of the deposited F:SnO2 thin-film. AC Impedance measurement was also done and film resistance of below 20 ohm/cm 2 was registered.
Thin Solid Films, 1996
The morphological, structural, optical and electrical properties of tin-oxide-based coatings, obtained by spray pyrolysis using an alcoholic solution of SnCl4, were studied. The fluorine concentration and profile in the deposited material were determined. Samples were produced at a substrate temperature of 300°C and a deposition time of 15 min.Undoped films showed a non-transparent milky appearance, an electrical resistivity of 33 x 10−4 ω cm and an optical transmittance of 70%–75% in the visible range. X-Ray and electron diffraction pattern results showed the presence of SnO2 in the cassiterite structure with a preferential growth in the (200) direction. Scanning electron micrographs showed that the surface coatings were covered by crystalline particles (size, 25 nm). Thin films obtained from NH4F solutions at fluorine concentrations in the range 1–40 wt.% showed a systematic decrease in the surface particle density and an increase in the transmittance with increasing fluorine concentration, attaining values around 85%. The resistivity decreased to 6 x 10−4 ω cm for doping in the 1–8 wt.% range, but for doping values above 8 wt.%, the resistivity increased more than fivefold.
Journal of Crystal Growth, 1998
Transparent electrically conducting tin oxide and fluorine doped tin oxide films were deposited on alkali-free corning borosilicate glass plates using ethanol and water mixture as solvent by spray pyrolysis in the temperature range 375-450°C. The structural, electrical and optical properties of these films were determined as a function of dopant incorporation in the basic spraying solution and the substrate temperature. Almost in all the cases the films were preferentially oriented along [1 1 0]. The visible transmittance as well as the electrical resistivity of the films decreased with the increase in the fluorine concentration. It has been observed that the best electro-optic properties, average transmittance of 88% and electrical resistivity of 10\ cm, were achieved with the fluorine doping concentration of around 57 at% in the solution at the optimized substrate temperature of 425°C.
Properties of fluorine-doped SnO2 films prepared by the spray pyrolysis technique
Physica Status Solidi (a), 1988
Fluorine-doped SnO 2 (SnO 2:F) films were prepared in ordinary atmosphere on heated Coming 7059 glass substrates by the pyrosol deposition method with solutions consisting of SnC14.5H20, NHaF, CH3OH, H20 and HCI. It was found that the substrate temperature and the chemical composition of the solutions largely affect the deposition rate and the properties of the SnO 2 : F films. Under the optimized deposition condition, a resistivity as low as-4.3 x 10-4 lI cm and a specular transmittance of = 79% could be attained for a-0.6 ixm thick film. X-ray diffraction measurements showed that these films were polycrystalline with the tetragonal cassiterite structure and grew with a (200) preferred orientation. The surface morphology observed by scanning electron microscopy changed from round-shape to pyramidal-shape above a substrate temperature of 450°C. A similar change in the surface morphology also took place when the CH3OH/H20 mol ratio in solution was less than 0.1. X-ray photoelectron spectroscopy indicated that the fluorine concentrations in the films, being significantly diminished, also increase with increasing the fluorine concentrations in the starting solutions.
Characterization of SnO2: F thin films deposited by an economic spray pyrolysis technique
physica status solidi …, 2010
Fluorine doped tin oxide (FTO) semiconductor thin films were deposited on glass substrates using spray pyrolysis technique and the effect of fluorine (F-) doping (varying 0-30 at %) is explored. X-ray diffraction studies confirmed the tetragonal structure with polycrystalline nature. The crystallinity of undoped films is enhanced with the increase in F-doping. The films doped with 25 at % F show a strong orientation along (101) plane. The grain size of the undoped films (214 nm) is increased with the increase in F-doping level to reach a maximum of 415 nm (25 at % F). A minimum sheet resistance of ~5.4 Ω/ obtained for the 30 at % F doped films is among the lowest reported values. The average visible transmittance (400-700 nm) of the undoped films (61.4 %) is increased with the increasing F-doping to reach a maximum of 74.5 % (25 at %. F). The films doped with 25 at. % F showed high value of figure of merit (4.55 × 10-3 Ω-1). The obtained results authenticate the influence of F-doping on the properties of the deposited films.
X-ray diffraction studies of electrostatic sprayed SnO2:F films
Microelectronics Journal, 2007
Fluorine-doped tin oxide films were deposited by electrostatic spray pyrolysis technique (ESP), on 1 cm  1 cm Corning 7059 substrates. The structural and electrical properties of the deposited films with different doping levels are studied. Relative variations in the structural properties were explained on the basis of structural factor calculations. The results show that the incorporation of fluorine atoms took place only at substitutional sites leading to an increase in free carrier concentration. r
Fluorine-doped tin oxide films with a high figure of merit fabricated by spray pyrolysis
Journal of Materials Research, 2015
Fluorine-doped tin oxide (FTO) thin films were deposited by spray pyrolysis in a pulse mode at 450°C on glass substrates, using an alcoholic solution of SnCl 4 Á5H 2 O and NH 4 F with different F/Sn ratios in the precursor solution. The film structure was nanocrystalline for all molar F/Sn ratios in the solution from 0 to 1.0. Postdeposition annealing treatments were not carried out. The films with a F/Sn 5 0.35-1.0 ratio present a high grain orientation in the (200) crystallographic plane. A minimum sheet resistance of 4.5 X/sq, a resistivity of 2.2 Â 10 À4 X cm, a maximum electron mobility of 21.6 cm 2 /V s, and a carrier concentration of 1.7 Â 10 21 cm À3 , corresponding to a strong degeneration of the electron gas in the conduction band, as well as a mean value of the transmittance of 0.84 in the visible spectral range, were obtained for the films fabricated with a F/Sn 5 0.5 ratio. A high value of the figure of merit was obtained using two methods (38.8 Â 10 À3 X À1 and 5.75 X À1), that is, comparable with the highest values reported to date.
Journal of Electroceramics, 2008
The electrical, optical, structural and chemical bonding properties of fluorine-doped tin oxide (SnO x :F) films deposited on a plastic substrate prepared by Electron Cyclotron Resonance-Metal Organic Chemical Vapor Deposition (ECR-MOCVD) were investigated with special attention to the process parameters such as the H 2 /TMT mole ratio, deposition time and amount of fluorine-doping. The four point probe method, UV visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic emission spectroscopy (AES), X-Ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the films. Based on our experimental results, the characteristics of the SnO x :F thin films were significantly affected by the process parameters mentioned above. The amount of fluorine doping was found to be one of the major parameters affecting the surface resistivity, however its excess doping into SnO 2 lead to a sharp increase in the surface resistivity. The average transmittance decreased with increasing film thickness. The lowest electrical resistivity of 5.0×10 −3 Ω. cm and highest optical transmittance of 90% in the visible wavelength range from 380 to700 nm were observed at an H 2 / TMT mole ratio of 1.25, fluorine-doping amount of 1.3 wt.%, and deposition time of 30 min. From the XRD analysis, we found that the SnO x :F films were oriented along the (2 1 1) plane with a tetragonal and polycrystalline structure having the lattice constants, a=0.4749 and c=0.3198 nm.