Fluorine doped tin oxide (FTO) thin films were deposited onto glass substrate at different substrate temperatures by a simple and inexpensive method of air pressure chemical vapor deposition. The substrate temperature was kept constant at about 500°C as the optimum temperature, and air was used as both a carrier gas and the oxidizing agent. A very simple method of characterization were carried on to investigate the electrical and structural properties of the prepared thin films. The electrical parameters variations showed that these parameters vary with substrate temperature ranging from an insulator thin film to a highly conductive layer. X-ray diffraction also revealed the structure to be polycrystalline at higher temperatures compared to amorphous structure for lower temperatures.
In this paper, the effect of substrate temperature on the electrical, structural, morphological and optical properties of nanostructured polycrystalline zinc oxide thin films were investigated by the Hall measurement, X-ray diffraction, scanning electron microscopy and UV-visible spectrophotometer, respectively. Then these modified thin films were deposited on two kinds of single crystal and polycrystalline of n- and p-type Si in three different substrate temperatures of 300, 400 and 500°C by low cost atmospheric pressure chemical vapor deposition method. Like the samples grown on the glass substrate, with increase of the temperature in samples grown on single crystal Si, preferred orientation changes from (100) to (002), while in samples deposited on poly crystalline Si, preferred orientation remains (100).
Nanostructured tin oxide (SnO_2) thin films have been prepared by spray pyrolysis technique. The effects of deposition conditions such as substrate temperature and tin chloride concentration in the precursor solution on physical properties of films have been investigated. The physical characterization of samples was carried out by UV-VIS spectroscopy, X-ray diffraction, scanning electron microscopy, and the Hall effect experiment for optical, structural, morphological and electrical studies, respectively. The films are polycrystalline in nature with a tetragonal crystal structure. The preferred orientation has been changed by changing the deposition parameters. In the case of changing the substrate temperature, (211) was found as the preferred orientation, while by changing the molarities of the solution, (301) orientation was grown as well as (211). The deposition temperature was optimized to 450°C; whereas the optimum solution concentration was found to be 0.2 mol/L. Films deposited at foregoing conditions have good optoelectrical properties which make them suitable for applying in different optoelectronic devices.
Thin films of acid-functionalized multiwall carbon nanotubes (O-MWCNT) with different concentrations and coated O-MWCNT with Fe_3O_4 nanoparticles (MWCNT/Fe_3O_4) were prepared on glass substrate at 300C by spray pyrolysis technique. In order to study the effect of nanotubes alignment on the physical properties of carbon nanotube films, thin film of iron oxide nanoparticles coated carbon nanotubes was deposited under magnetic field of 0.4 T. All samples were characterized using UV-Vis spectroscopy, X-ray diffraction, scanning electron microscopy, and the Hall effect experiment. Results show that the electrical conductivity and optical transmittance of carbon nanotubes thin films depend on the concentration of carbon nanotubes and their arrangement at the films. Aligning carbon nanotubes in thin films leads to an obvious improvement in electrical and optical properties of thin films.
The importance of vanadium oxide in solid state science as a semiconductor encouraged us to prepare and investigate its microstructure and surface properties related to gas sensing characteristics. Hence, vanadium oxide thin films were deposited by spray pyrolysis method. The prepared films were placed in an electric circuit and the sensing characteristics of these films to ethanol vapors were studied. It was possible to find correlations between nanostructure and electrical properties of the obtained thin films and to optimize conditions of its synthesis. By X-ray diffraction, field emission scanning electron microscopy, and atomic force microscopy, the structure of the deposited films was determined. Based on atomic force microscopy results, the fractal analysis showed a decreasing trend of the fractal dimension (the slope of the log (perimeter) vs. log (area)) versus the deposition time. It was found that the film growth and gas response were affected by the deposition time. The operating temperature of the sensor was optimized for the best gas response. In accordance with our findings, the film deposited at the lowest deposition time (20 min) had the highest sensing response to ethanol.
Indium oxide (In_2O_3) thin films were deposited on glass substrate by varying substrate temperature in the range of 400-600C using the spray pyrolysis technique. In this research, physical properties of indium oxide thin films were studied and then nanocrystalline sizes at different substrate temperature were deeply compared and investigated. All films were characterized at room temperature using X-ray diffraction, scanning electron microscopy, atomic force microscopy, photoluminescence, the Hall effect and UV-visible spectrophotometer. The optimal substrate temperature to obtain films of high crystallographic quality was 575°C, for this temperature, the electrical resistivity was in the order of ρ=0.147 Ω cm. For comparing optical transmittance and electrical conductivity the best figure of merit of the films was achieved at 575C.
Thin films of acid-functionalized multiwall carbon nanotubes (O-MWCNT) with different concentrations and coated O-MWCNT with Fe_3O_4 nanoparticles (MWCNT/Fe_3O_4) were prepared on glass substrate at 300°C by spray pyrolysis technique. In order to study the effect of nanotubes alignment on the physical properties of carbon nanotube films, thin film of iron oxide nanoparticles coated carbon nanotubes was deposited under magnetic field of 0.4 T. All samples were characterized using UV-Vis spectroscopy, X-ray diffraction scanning electron microscopy and the Hall effect experiment. Results show that the electrical conductivity and optical transmittance of carbon nanotubes thin films depend on the concentration of carbon nanotubes and their arrangement at the films. Aligning carbon nanotubes in thin films leads to an obvious improvement in electrical and optical properties of thin films. Results show that the electrical conductivity and optical transmittance of carbon nanotubes thin films depend on the concentration of carbon nanotubes and their arrangement at the films. Aligning carbon nanotubes in thin films leads to an obvious improvement in electrical and optical properties of thin films.
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