Papers by Keyword: Deposition Temperature

Abstract: Barium strontium titanate (Ba_0.8Sr_0.2TiO₃) thin films have been prepared by pulsed laser deposition (PLD). The thin film of (Ba_0.8Sr_0.2TiO₃) was deposited on a silicon (Si) substrate with different deposition temperatures. The XRD pattern identifies these specimens as being of the tetragonal phase. As the deposition substrate temperature varied from 200 °C to 400 °C, the average crystal size of BST increased from 34 nm to 68 nm calculated by the XDR pattern. Field (FESEM) images have estimated the particle size of the film. The dielectric constant increased with increasing substrate temperature.

Abstract: Synthesize of Boron Nitride nanowires were made by utilizing Austenitic hardened steel AISI 316 with a nitriding layer of 15–16 μm thickness. Deposition experiments at deferent substrate temperatures for BN Nanowires productions were carried out with the help of a blended gas stage depositing handle procedure (PVD and CVD). Chemical composition and crystallinity along with the average grain size for BN phases was investigated by using XRD test and FTIR spectrum. The SEM images was used to examine the surface topography. Finally theoretical investigations computations were performed by thickness useful hypothesis (DFT) in Gaussian 09 bundle. According to our results, the impact of the depositing temperature on the chemical composition and the structure should be pointed out as the major effect for the higher deposition rate that leads to thicker and more dense BN surface film, where the more uniform BN Nanostructures wires with a regular diameter of 20 nm and average grain size of ~18nm was compelled through novel materializing crystalline stages causing grain size to rise with increasing deposition temperature to specific level.

Abstract: SiBCN powders have been prepared by chemical vapor deposition using borazine and liquid polycarbosilane as source precursors in the deposition temperature range from 800 °C to 1100 °C, with the pressure of 10 kPa. The effect of the temperatures on the surface morphologies of the as-received powders was investigated by SEM. FTIR analysis of the powders was used to obtain the composition of the powders, and the XRD analysis was used to determine the crystalline state of the deposits. The results showed the powders were amorphous and composed of normally spherical grains.

Abstract: The VN coatings were coated by chemical vapor deposition on T12 substrate using V₂O₅, H₂ and N₂ as reactants. Thermodynamic calculation and analysis of formation reaction of VN were done by thermodynamic potential function. As shown by the experimental results, chemical vapor deposition of the VN coating with preheating temperature of 973K and deposition temperature of 1573K under normal atmospheric pressure was feasible.

Abstract: Well-aligned arrays of vertically oriented ZnO nanorods were synthesized using hydrothermal method using equal molar concentration of zinc acetate hexahydrate (Zn (CH₃COO)₂.6H₂O) and hexamethylenetetramine (C₆H₁₂N₄) at various deposition temperatures. The resulting nanorods were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL), and UV-vis spectrophotometer. XRD and FESEM results indicate that the crystallinity improved for nanorods grown at 85 °C. The preferred growth direction of these nanorods is in (002) direction. However, the nanorods were grown at 55 °C shows poor crystalline characteristics. Typically, these nanorods have grown up to 1000 nm with the diameter range of 25-50 nm. The obtained ZnO nanorods exhibit a weaker UV emission peak located around ~380-390 nm and a relatively stronger yellow-red emission band located at 625 nm to 675 nm.

Abstract: ZnO in various nanostructures forms have been widely studied for the application such as in solar cells, light emitting diodes, UV sensors and so on. In this paper, we have successfully deposited ZnO nanotetrapods using thermal chemical vapour deposition (TCVD) technique on layer-by-layer ZnO seeded catalyst, with Zn powder and O₂ gas as source materials. We demonstrate that by using double furnace TCVD system, ZnO nanotetrapods can be deposited at lower temperature than the vapour temperature of the Zn powder. In this paper we report the effect of different deposition temperature (450 °C to 600 °C) on the surface morphologies, crystalline structure and optical properties of the ZnO nanotetrapods. FE-SEM micrographs show that the length of the nanotetrapods arms decreases with the increase of the deposition temperature. PL spectra show that the visible emission are very low compared to the UV emission which indicates that the ZnO tetrapod have very low intrinsic defect. The highest UV emission intensity is given by the sample deposited at 500 °C.

Abstract: 80nm-thick network Ni films were sputter-deposited on anodic aluminium oxide (AAO) substrates at 300 K and 573 K. The network films are formed by granule connection. The granule consists of many fine grains. Both granule size and grain size are independent of the deposition temperature. A temperature dependence of the resistance within 1.6-300 K reveals that the network Ni film grown at 300 K exhibits a minimal resistance at about 25 K while that grown at 573 K does not show a minimal resistance. A temperature coefficient of resistance of the network film grown at 573 K is larger than that of the film grown at 300 K.

Abstract: CdZnS thinfims have been prepared on mineral glass substrate by spray pyrolysis method at different deposition temperature using the optimized coating parameters. The XRD profile of the films confirms hexagonal wurtizite structure with preferred orientation along the (101) pane. The different crystallographic parameters viz., lattice constant, c/a ratio, mean grain size, number of reflections per unit area, lattice strain, dislocation density, texture coefficient and standard deviation have been calculated from the experimentally observed XRD data and the effect of deposition temperature on these parameters have been elaborately discussed. The maximum optical transmittance of 84.5% (at λ= 650 nm ) has been observed for the CdZnS thin film spray deposited at the temperature 450 °C. The direct band gap energy calculated from the transmittance measurements lies between 2.82 eV and 3.4 eV. The electrical resistivity has been found to be low with the value 50 x 103 Ω - cm for the film deposited at the temperature 450 °C. The SEM micrographs of the films show uniform surface pattern associated with large accumulation of fine grains. The grain size estimated from the SEM analysis lies between 100 nm and 350 nm.

Abstract: Nanocrystalline silicon (nc-Si) thin films were deposited on glass and polytetrafluoroethylene (PTFE, teflon) substrates using Radio frequency (RF) magnetron sputtering. The effect of RF power and deposition temperature on the physical and structural properties of nc-Si on the glass and Teflon substrate was studied. The thin films properties were examined by Raman spectroscopy and field emission scanning electron microscopy (FESEM). We found that the thickness of thin films increased with increased RF power and deposition temperature. Raman spectroscopy results it showed that, with increasing RF power and deposition temperature can cause the changing of crystallinity on both glass and Teflon substrate.

Abstract: Deposition temperature is a key factor influencing the growth morphology of thin-films, aiming at this phenomenon, a precise control system of deposition temperature in ultra-high vacuum is developed in the paper. It can realize accurate temperature control in a range of 150K to 450K during experiment by combination of resistance heating up and liquid helium cooling down strategies, which is benefit to further understand the temperature-depended mechanism of organic molecule thin-film growth. Besides, it is experimentally studied that the growth morphology of p-6p molecules on a mica substrate is closely related to the substrate deposition temperature, indicating that the length of p-6p nano-fibers is proportional to the deposition temperature, while their distribution density is inversely proportional to the temperature.