Sharif Digital Repository

The micromorphology and semiconductor properties of TiO2 thin films growth using different ion beam energies have been finely analyzed using atomic force microscopy (AFM), ultra-violet visible (UV–visible) spectroscopy and stereometric analysis. The AFM measurements and surface stereometric analysis are essential for the accurate characterization of the 3-D surface topographic features and allow the determination of the 3-D surface texture parameters that influence the optical properties of the material. The samples were divided into four groups to discuss the obtained results, according to the ion beam energy applied in the sample preparation. The results obtained from experimental... 

In this study, ZrO2 coatings with different thicknesses were grown by the electron beam evaporation technique. The crystalline structure was studied by XRD analysis which suggested the tetragonal and monoclinic phases for ZrO2 coatings. Additionally, the film thickness slightly enhanced the crystallinity. The surface morphology and fractal features were analyzed using Scanning Electron Microscopy (SEM). The surface statistical parameters and the fractal geometry were employed to analyze the impact of the coating thickness and homogeneity on the morphology of the films. The statistical processing and fractal dimension revealed variations in the morphology parameters due to the electron beam... 

Nowadays, fossil fuel limitations and environmental concerns push researchers to find clean and renewable energy resources. Solar hydrogen production via water splitting reactions in electrochemical and/or photo-electrochemical systems has been accepted as a promising route and efficient electrocatalysts are involved in both. Here, cobalt nanoflakes with an oxide/hydroxide surface and a conductive metallic core are grown on commercially available steel mesh modified with carbon based nanocomposites as a support layer. The portion of reduced graphene oxide sheets was changed from 0 to 100 wt% and the correlation of this concentration with the surface morphology and electro-catalytic activity... 

Thin films of bismuth and iron oxides were obtained by atomic layer deposition (ALD) on the surface of a flexible substrate poly(4,4′-oxydiphenylene-pyromellitimide) (Kapton) at a temperature of 250°C. The layer thickness was 50 nm. The samples were examined by secondary-ion mass spectrometry, and uniform distribution of elements in the film layer was observed. Surface morphology, electrical polarization, and mechanical properties were investigated by atomic force microscope, piezoelectric force microscopy, and force modulation microscopy. The values of current in the near-surface layer varied in the range of ±80 pA when a potential of 5 V was applied. Chemical analysis was performed by... 

Experimental parameters have direct influences on materials properties and therefore their applications. The effect of plasma power on the properties of cobalt oxide thin films, prepared using plasma-enhanced chemical vapor deposition technique, on stainless steel substrates have been addressed in this paper. The structural, morphological, and compositional properties of these films were investigated by means of X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) technique. The XRD patterns demonstrated the growth of polycrystalline Co3O4 thin film with a cubic spinel structure such that the intensity of (511) and (311) peaks increase as the... 

The micromorphology of tantalum pentoxide (Ta2O5) thin films, deposited on glass substrates by electron gun method, has been analyzed using atomic force microscopy (AFM), UV–Vis–NIR spectrophotometry and multifractal analyses. Two samples were grown at basic pressure of 7 × 10−6 mbar, work pressures of 1.3 × 10−4 and 2.0 × 10−4 mbar, and thicknesses of 0.38 μm and 0.39 μm, respectively. Subsequently, these samples were annealed at 300 °C for 2 h. The physical, structural and optical analyses were investigated by spectroscopic ellipsometry, spectrophotometry and AFM. The measured transmittance spectra were studied based on the Swanepoel method, whose results also yielded to the estimation of... 

The morphology, structure and optical properties of zinc sulfide (ZnS) thin films prepared through radio-frequency (RF) magnetron sputtering have been analyzed using atomic force microscopy (AFM), UV–Vis–NIR spectrophotometry, X-ray diffraction, and multifractal analyses. The X-ray diffraction patterns revealed that all ZnS thin films show a single peak at around 29.6°, which has been ascribed to the (111) planes of sphalerite phase, indicating that the growth direction of the films is the [111] direction. UV–Vis–NIR transmittance spectra were used to determine the refractive index of the samples, their thickness, and their band gap energy, showing the optical and semiconductor properties a... 

In this study, plasmonic properties of transition metal atoms (Sc-Zn, Pd, Pt) adsorbed on various sites of graphene sheets were investigated before and after CO adsorption by density functional theory (DFT). To this aim, Electron Energy Loss Spectroscopy (EELS) of these systems were obtained by periodic DFT. The results indicated that the highest in-plane plasmon peaks undergo blue shifts after CO adsorption, in such a way that Co–graphene system demonstrates the highest blue shift of 2.42 eV from Visible to UV region. Also, out-of-plane plasmons do not exhibit significant sensitivity to CO adsorption. For deeper understanding of electronic structure of metal-graphene systems, appropriate... 

In this paper, we have successfully deposited Ag-Cu thin films. Nanoscale morphology and nanotexture were studied using atomic force microscopy (AFM) through fractal and stereometric parameters. Additional algorithms have been developed to study new fractal parameters such as surface entropy, fractal succolarity, and fractal lacunarity. The results revealed that as the deposition time increased, films exposed isotropies between ~65 and 82%, which were correlated to the fractal patterns, where from #3 to #5 there were greater spatial complexities. Moreover, surface roughness increased from #1 to #3, which was observed for both Sq and Sa. Similar behavior was exhibited by the other height... 

Purpose: The morphological stability of silicon single crystal wafers was investigated, after performing cleaning surface treatments based on moderate temperature annealing and plasma sputtering. Methods: The wafer surfaces were measured by Tapping mode atomic force microscopy in air, before and after the different treatments. The 3D images were segmented by watershed algorithm identifying the local peaks, and the stereometric parameters were extracted thereof. The analysis of variance allowed to better assess the statistically significant differences. Results: All the resulting quantities were critically discussed. It appeared that the different cleaning treatments affected differently the... 

Material characteristics and input-field specifics limit controllability of nonlinear electromagnetic-field interactions. As these nonlinear interactions could be exploited to create strongly localized bright and dark waves, such as nonlinear surface polaritons, ameliorating this limitation is important. We present our approach to amelioration, which is based on a surface-polaritonic waveguide reconfiguration that enables excitation, propagation and coherent control of coupled dark rogue waves having orthogonal polarizations. Our control mechanism is achieved by finely tuning laser-field intensities and their respective detuning at the interface between the atomic medium and the metamaterial... 

Knowing the exact pressure of the process has a great impact on the validity of the results, product quality, energy efficiency, and in some processes, on the security of work with the system. Hence, the calibration of the barometers and the accuracy of the readings should be taken seriously. Choosing the appropriate time interval for re-calibration is done according to the extent and conditions of use, uncertainty, and the inaccuracy allowed in measurement, constructive suggestion, and some other things. Failure to pay attention to the importance of periodic calibration in vacuum gauges leads to some irreparable losses in the research project and the vacuum generator system. In this study,...