Properties Of Thin Film Layers Research Articles

Electrical Conductivity of Reduced Graphene Oxide Thin-Film Layers

This work deals with the research of the electric properties of thin film layer of reduced graphene oxide. A structure of graphene oxide (GO) is represented by randomly distributed on a surface of substrate small islets of graphene with sp2 hybridized bonds surrounded by wide areas with sp3 bonds functionalized by oxygen groups. When electrons are confined in two-dimensional materials, quantum-mechanically enhanced transport phenomena such as the quantum Hall effect can be observed. Reduced graphene oxide, consisting of an isolated single atomic layer of graphite, is an ideal realization of such a two-dimensional system, therefore the partly semiconductive properties could be observed.

Spectroscopic ellipsometry study of silver nanospheres and nanocubes in thin film layers

Selective control of the optical properties of thin film layers is necessary in various domains such as photovoltaics and optoelectronics. Through localized surface plasmon resonance, silver nanoparticles exhibit selective optical properties in the visible wavelength range depending on their size and shape. The tremendous progress in nanoparticle synthesis methods, leads to easy fabrication of nanoparticles of various sizes and shapes. By embedding various nanoparticles in a thin film layer, the optical properties are engineered. Silver nanospheres and nanocubes are synthetized by a modified polyol process and randomly deposited in a non-absorbing polymer host matrix. Spectroscopic ellipsometry characterizations determine the complex optical indices of single shape nanoparticles, two shaped nanoparticles and multilayer configuration thin film layers. The spectroscopic ellipsometry data are fitted by a Cauchy law, accounting for the optical properties of the polymer host matrix, and one or several Gauss laws, accounting for the optical properties of the nanoparticles. The extinction coefficient of the blend and multilayer layers show a simple superposition of the extinction coefficients. Therefore, the nanoparticles do not interact in the thin film layers.

Investigation of optical and chemical properties of poly(3-methylthiophene) and polypyrrole for solar cell fabrication

In this study, we have investigated the optical and chemical properties of thin film layers based on poly(3-methylthiophene) and polypyrrole through experiment and simulation point of view. Optical band gap of poly(3-methylthiophene-co-pyrrole) (poly(3-MeT-co-py)) and poly(3-methylthiophene) (PMeT) were investigated through UV–vis spectroscopy. Electrochemical data were used to estimate the onset oxidation and reduction potential, energy band diagram and chemical band gap of PMeT and poly(3-MeT-co-py). The experiments were carried out in a three-electrode cell with ITO as the working electrode. Influence of different electrodes on PMeT thin film's energy levels was studied in electrochemical polymerization. Different thin films by poly(3-methylthiophene) and polypyrrole were utilized in order to fabricate organic solar cells and their photovoltaic properties were offered. Moreover, an optical modeling based on thin film matrix formalism has been carried out which investigated absorption processes in single layer solar cell by PMeT. From the simulation, photons absorbed profiles and energy dissipation in term of wavelength and distance in depth of cell were derived in active layer.

UV optical properties of thin film oxide layers deposited by different processes

UV optical properties of thin film layers of compound and mixed oxide materials deposited by different processes are presented. Japan Electron Optics Laboratory plasma ion assisted deposition (JEOL PIAD), electron beam with and without IAD, and pulsed DC magnetron sputtering were used. Comparisons are made with published deposition process data. Refractive indices and absorption values to as short as 145 nm were measured by spectroscopic ellipsometry (SE). Electronic interband defect states are detected that are deposition-process dependent. SE might be effective in identifying UV optical film quality, especially in defining processes and material composition beneficial for high-energy excimer laser applications and environments requiring stable optical properties.

The acoustic properties of oxide films and their application to acoustic surface wave devices

Surface acoustic wave techniques represent a powerful tool for the study of the elastic properties of thin film layers. Simple arrays of interdigital transducers can be used to measure the velocity, attenuation, and piezoelectric properties of oxide films. Results of such measurements on zinc oxide and silicon dioxide films are given and the values compared to their bulk counterparts. High acoustic quality oxide films can be used effectively to enhance the performance of surface acoustic wave devices. Potential application areas are briefly summarized.