Sharif Digital Repository

Co-deposition of RF-sputtering and RF-PECVD from acetylene gas and Au target were used to prepare sensor chip of gold nanoparticles (Au NPs). Deposition conditions were optimized to reach a Localized Surface Plasmon Resonance (LSPR) sensor chip of Au NPs with particle size less than 10 nm. The RF power was set at 180 W and the initial gas pressure was set at 0.035 mbar. Transmission Electron Microscopy (TEM) images and Atomic Force Microscopy (AFM) data were used to investigate particles size and surface morphology of LSPR sensor chip. The Au and C content of the LSPR sensor chip of Au NPs was obtained from X-ray photoelectron spectroscopy (XPS). The hydrogenated amorphous carbon (a-C:H)... 

Polymeric like carbon (PLC) films are grown by a capacitance coupled RF-PECVD on the grounded electrode at room temperature from liquid gas (40% propane and 60% butane) in two regimes with nitrogen and without nitrogen gas. Films are characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Fourier transform infrared (FTIR) absorption and Raman spectroscopy. The result of FTIR analyses indicates that more than 90% of hydrogen atoms are bonded to carbon with sp 3 hybridization. The abundance of CH 3 is more than that of CH 2 and this one is more than that of CH for carbon with sp 3 hybridization in these films. The C 1s line of the XPS spectra is deconvoluted to... 

Hexagonal array of Cu@CuO core-shell nanoparticles (NPs) on the a-C:H thin film was prepared by codeposition of RF-sputtering and RF-PECVD. The trace of hexagonal NPs supperlattice was recognized by AFM image and XRD result. On the basis of localized surface plasmon resonance (LSPR) of core-shell NPs, the prepared array detected a low flow rate of CO gas at room temperature. XPS results indicate that the surface of Cu@CuO core-shell NPs have no chemical reaction with CO molecule. The physical absorption of CO molecule on the surface of Cu@CuO core-shell NPs increases the LSPR absorbance and causes a red shift in LSPR wavelength. These experimental results are in agreement with Mie theory... 

By co-deposition via RF-Sputtering and RF-PECVD methods and using Cu target and acetylene gas, we prepared Cu@Cu2O coreshell nanoparticles on the a-C:H thin film at room temperature. Mie absorption of Cu cores, scattering from Cu2O shell and luminescence that rises from carrier transfer in Cu@Cu2O interface were employed to fit the whole range of visible extinction spectrum of these coreshells. From simulation it was found that scattering and luminescence have an important effect on the energy, width and shape of LSPR absorption peak. Shift of LSPR peak is more affected by the dielectric coefficient of shell than Cu core size particularly for Cu core diameter above 4 nm. Also, the LSPR... 

We prepared Cu nanoparticles in a-C:H thin films by co-deposition of RF-sputtering and RF-PECVD methods at room temperature. By increasing Cu content in these films a nonmetalmetal (NM) transition is observed. This transition is explainable by the power law of percolation theory. The critical metal content is obtained 56% and the critical exponent is obtained 1.6, which is larger than the exponent for 2 dimension systems and smaller than the one for 3 dimension systems. The electrical conductivity of dielectric samples was explained by tunneling. Activation tunneling energy that was obtained from temperature dependence of electrical resistivity correlates with near infrared absorption peak... 

Cu@Cu2O core-shell nanoparticles on a-C : H thin films are prepared by co-deposition of RF-sputtering and RF-PECVD. Samples with different copper concentrations are grown. The copper content of films increases with reduction in initial pressure and rises with increasing RF power. When the Cu/C ratio reaches 0.5, the surface plasmon resonance (SPR) peak that is a signature of the formation of Cu nanoparticles appears in visible spectra of these films. X-ray photoelectron spectroscopy (XPS) characterization indicates that the surface of the copper nanoparticles oxidizes when they are exposed to air. The results are indicative that the shell of the nanoparticle is mainly the Cu 2O phase that is... 

We report optical and electrical properties of Cu-Ni nanoparticles in hydrogenated amorphous carbon (Cu-Ni NPs @ a-C:H) with different surface morphology. Ni NPs with layer thicknesses of 5, 10 and 15 nm over Cu NPs @ a-C:H were prepared by co-deposition of RF-sputtering and RF-Plasma Enhanced Chemical Vapor Deposition (RF-PECVD) from acetylene gas and Cu and Ni targets. A nonmetal-metal transition was observed as the thickness of Ni over layer increases. The surface morphology of the sample was described by a two dimensional (2D) Gaussian self-affine fractal, except the sample with 10 nm thickness of Ni over layer, which is in the nonmetal-metal transition region. X-ray diffraction profile... 

We prepared copper-carbon nanocomposite films by co-deposition of RF-Sputtering and RF-PECVD methods at room temperature. These films contain different copper concentration and different size of copper nanoparticles. The copper content of these films was obtained from Rutherford Back Scattering (RBS) analyze. We studied electrical resistivity of samples versus copper content. A metal-nonmetal transition was observed by decreasing of copper content in these films. The electrical conductivity of dielectric and metallic samples was explained by tunneling and percolation models respectively. In the percolation threshold conduction results from two mechanisms: percolation and tunneling. In the...