Search Results

101 - 110 of 444 items :

  • "thin films" x
Clear All
Improvement of Solar PV Efficiency. Potential Materials for Organic Photovoltaic Cells

. 5. Sun, S-S., Sariciftci, N.S. Organic Photovoltaics: Mechanisms, Materials, and Devices (Optical Science and Engineering), CRC Press, Taylor and Francis Group, 2005 6. Brabec, J.C., Dyakonov, V., Parisi, J., Sariciftci, N.S. Organic photovoltaics. Concepts and realization, Springer-Verlag, Berlin, Heidelberg, 2003 7. Peumans, P., Yakimov, A., Forrest, S.R. Small molecular weight organic thin-film photodetectors and solar cells, J. Appl. Phys. 93, 2003, p. 3693-3723. 8. Gunes, S., Neugebauer, H., Sariciftci, N

Open access
Effect of Sm concentration on optical and electrical properties of CdSe nanocrystalline thin film

Abstract

Present paper reports optical and electrical properties of samarium doped CdSe nanocrystalline thin film which was grown on a glass substrate by chemical bath deposition method (CBD). X-ray diffraction (XRD) analysis revealed that the deposited films were nanocrystalline with sphalerite cubic structure. The average crystallite size calculated from FWHM of XRD peaks was found to be 10.11 nm. The bandgap of the Sm doped CdSe nanocrystalline thin films was calculated to be 1.91 eV to 2.22 eV. The optical absorption edge of undoped (pure) and Sm doped CdSe films was obtained between 650 nm to 640 nm showing blue shift as compared to bulk CdSe. Sm doping further enhanced the photoconductivity of these films. The I-V characteristic confirmed the suitability of prepared films for photosensor applications.

Open access
Morphology, microstructure and magnetic properties of thermionic vacuum arc deposited NiFeCu ferromagnetic thin films

Abstract

NiFeCo granular ferromagnetic thin films were deposited on glass and silicon wafer substrates in thermionic vacuum arc plasma with simultaneous ignition of plasma in Cu and NiFe vapors. The structural and morphological properties of the prepared films were investigated by TEM Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). Elemental composition of the films was revealed after X-ray energy dispersive spectroscopy analysis (EDAX). The magneto-optical longitudinal Kerr rotation spectra of the samples were also measured and compared.

Open access
Development of Mathematical Models for Detecting Micron Scale Volumetric Defects in Thin Film Coatings

Abstract

The focus of the present research is to investigate possibilities of volumetric defect detection in thin film coatings on glass substrates by means of high definition imaging with no complex optical systems, such as lenses, and to determine development and construction feasibility of a defectoscope employing the investigated methods. Numerical simulations were used to test the proposed methods. Three theoretical models providing various degrees of accuracy and feasibility were studied.

Open access
Sol-Gel Derived Cds Nanocrystalline Thin Films: Optical and Photoconduction Properties

Abstract

High-quality CdS nanocrystalline thin films were grown by sol-gel spin coating method at different solution temperatures on glass substrates. As-deposited films exhibited nanocrystalline phase with hexagonal wurtzite structure and showed good adhesion and smooth surface morphology. It was clearly observed that the crystallinity of the thin films improved with the increase in solution temperature. Crystallites sizes of the films also increased and were found to be in the range of 10 mm to 17 nm. The influence of the growth mechanism on the band and sub-band gap absorption of the films was investigated using UV-Vis and photothermal deflection spectroscopy (PDS). The band gap values were calculated in the range of 2.52 eV to 2.75 eV. The band gap decreased up to 9 % with the increase in solution temperature from 45 °C to 75 °C. Absorption coefficients estimated by PDS signal showed the significant absorption in low photon energy region of 1.5 eV to 2.0 eV. The dark and illuminated I-V characteristics revealed that the films were highly photosensitive. The results demonstrated the potential applications of sol-gel grown CdS nanocrystalline thin films as photoconductors and optical switches.

Open access
Preparation and spectroscopic analysis of zinc oxide nanorod thin films of different thicknesses

Abstract

Zinc oxide thin films with different thicknesses were prepared on microscopic glass slides by sol-gel spin coating method, then hydrothermal process was applied to produce zinc oxide nanorod arrays. The nanorod thin films were characterized by various spectroscopic methods of analysis. From the images of field emission scanning electron microscope (FESEM), it was observed that for the film thickness up to 200 nm the formed nanorods with wurtzite hexagonal structure were uniformly distributed over the entire surface substrate. From X-ray diffraction analysis it was revealed that the thin films had good polycrystalline nature with highly preferred c-axis orientation along (0 0 2) plane. The optical characterization done by UV-Vis spectrometer showed that all the films had high transparency of 83 % to 96 % in the visible region and sharp cut off at ultraviolet region of electromagnetic spectrum. The band gap of the films decreased as their thickness increased. Energy dispersive X-ray spectroscopy (EDS) showed the presence of zinc and oxygen elements in the films and Fourier transform infrared spectroscopy (FT-IR) revealed the chemical composition of ZnO in the film.

Open access
Cold plasma in the nanotechnology of catalysts

., Nakashima H., Muraoka K.: Plasma breaking of thin films into nano-sized catalysts for carbon nanotube synthesis, Mater. Sci. Eng. A , 2003 , 352 , 308. Rossnagel S. M., Cuomo J. J., Westwood W. D.: (Ed.), Handbook of Plasma Processing Technology; Fundamentals, Etching, Deposition, and Surface Interactions, Noyes Publ., Park Ridge, New Jersey, USA, 1990 . Thomann A. L., Rozenbaum J. P., Brault P., Andreazza C., Andreazza P., Rousseau B., Estrade-Szwarckopf H., Berthet A., Bertolini J. C., Aires F. J. C. S., Monnet F

Open access
Structural and surface analysis of chemical vapor deposited boron doped aluminum nitride thin film on aluminum substrates

Abstract

Chemical vapor deposition (CVD) process was conducted for synthesis of boron (B) doped aluminum nitride (B-AlN) thin films on aluminum (Al) substrates. To prevent melting of the Al substrates, film deposition was carried out at 500 °C using tert-buthylamine (tBuNH2) solution delivered through a bubbler as a nitrogen source instead of ammonia gas (NH3). B-AlN thin films were prepared from three precursors at changing process parameters (gas mixture ratio). X-ray diffraction (XRD) technique and atomic force microscope (AFM) were used to investigate the structural and surface properties of B-AlN thin films on Al substrates. The prepared thin films were polycrystalline and composed of mixed phases {cubic (1 1 1) and hexagonal (1 0 0)} of AlN and BN with different orientations. Intensive AlN peak of high intensity was observed for the film deposited at a flow rate of the total gas mixture of 25 sccm. As the total gas mixture flow decreased from 60 sccm to 25 sccm, the crystallite size of AlN phase increased and the dislocation density decreased. Reduced surface roughness (10.4 nm) was detected by AFM for B-AlN thin film deposited on Al substrate using the lowest flow rate (25 sccm) of the total gas mixture.

Open access
SHI irradiation induced modifications of plasmonic properties of Ag-TiO2 thin film and study using FDTD simulation

Abstract

Modifications in morphological and plasmonic properties of heavily doped Ag-TiO2 nanocomposite thin films by ion irradiation have been observed. The Ag-TiO2 nanocomposite thin films were synthesized by RF co-sputtering and irradiated by 90 MeV Ni ions with different fluences. The modifications in morphological, structural and plasmonic properties of the nanocomposite thin films caused by ion irradiation were studied by transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-Vis absorption spectroscopy. The thickness of the film and concentration of Ag were assessed by Rutheford backscattering (RBS) as ~50 nm and 56 at.%, respectively. Interestingly, localized surface plasmon resonance (LSPR) appeared at 566 nm in the thin film irradiated at the fluence of 1 × 1013 ions/cm2. This plasmonic behavior can be attributed to the increment in interparticle separation. Increased interparticle separation diminishes the plasmonic coupling between the nanoparticles and the LSPR appears in the visible region. The distribution of Ag nanoparticles obtained from HR-TEM images has been used to simulate absorption spectra and electric field distribution along Ag nanoparticles with the help of FDTD (Finite Difference Time Domain). Further, the ion irradiation results (experimental as well simulated) were compared with the annealed nanocomposite thin film and it was found that optical properties of heavily doped metal in the metal oxide matrix can be more improved by ion irradiation in comparison with thermal annealing.

Open access
Preparation of cubic alumina and scandia doped zirconia and its thin film fabrication by pulsed laser deposition technique

Abstract

Alumina and scandia doped zirconia was prepared through a soft chemistry synthesis route and sintered at 1873 K. X-ray diffraction patterns indicate a pure cubic phase for the composition of 0.88ZrO2-0.112Sc2O3-0.008Al2O3. Thin films were fabricated on Al2O3 〈0001〉 substrates using pulsed laser deposition technique. Dense films of 0.941 μm thickness were obtained at 873 and 1023 K substrate temperatures at an oxygen partial pressure of 15 Pa. The ionic conductivity of both thin film and sintered pellet was measured using ac impedance spectroscopy in air. The conductivity values are higher for thin films compared to that of sintered pellets.

Open access