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In this study, a new design of 1 x 2 photonic crystal beam splitters is proposed to achieve symmetrically higher power splitting. Two different splitters based on hybrid couplers made from silicon (Si) and poly(methyl methacrylate) (PMMA) materials were studied. One splitter had two outputs, and the other had four outputs. The PMMA temperature was varied from 0 °C to 130 °C to enhance the optical performance of the proposed splitters. The power intensity and photonic band gap (PBG) values were numerically investigated using the finite-difference time-domain (FDTD) and plane wave expansion (PWE) methods. The effect of temperature on these values was also studied to obtain the optimal conditions for high efficiency. The efficiency values were satisfactory. They could reach 49.9 % from the two output ports at a temperature of 80 °C. [ABSTRACT FROM AUTHOR]

In this work, we prepared a nanostructure of TCO in a thin film of tin oxide using the spray pyrolysis method. The different deposition parameters have been set and optimized to prepare the source solution from Tin chloride dihydrate deposited on a cleaned glass substrate. The characterization of the thin layer of pure tin oxide deposited by spraying was achieved. The X-ray diffractometer shows that the tin oxide film is polycrystalline with a tetragonal structure, which consists mainly of orientations (101), (211) and other less intense. Ultra-violet-spectroscopy approved an excellent transparency of the thin layer of pure SnO2 with a transmission of 95 % at 600 nm. The optical gap value of the deposited sample is equal to 3.95 eV. The spectroscopic ellipsometry measurements of the Psi and delta parameters were carried out at various angles of incidence 65°, 70° and 75°. The optical constant of the SnO2 layer was modeled using a B-spline model. The goodness of the ellipsometric fitting was found at an incidence angle of 75°, which indicates a minimum MSE equal to 4.022. The SE characterization results of SnO2 thin film on the glass substrate have shown that the layer thickness, the refractive index and the extinction coefficient are equal to 219.78 nm, 1.41 and 0.123, respectively. The resulting structural and optical parameters confirmed that a thin SnO2 layer was formed. This layer showed a wide bandwidth and high transparency of a type of TCO semiconductor, which can be used as an anti-reflective layer in solar cell devices. [ABSTRACT FROM AUTHOR]

The effect of thermal annealing on the optical and physicochemical properties of hydrogenated silicon nitride films was studied. These films were deposited by plasma-enhanced chemical vapor deposition from a mixture of silane, ammonia, and nitrogen. Subsequently, the films were annealed at various temperatures ranging from 400°C to 1000°C. The properties of the films were studied using ellipsometry and Fourier transform infrared spectroscopy. The Maxwell Garnet model considers the silicon nitride material as heterogeneous with three distinct phases: silicon, stoichiometric silicon nitride, and hydrogen. Based on the ellipsometric analysis, the annealing treatment leads to reduce the volume fraction of both hydrogen and silicon. As a result, the stoichiometry parameter significantly increases from 1.24 to 1.32 making it closer to the stoichiometric silicon nitride one. According to the infrared data, a noticeable decrease in the total hydrogen concentration in the films was obtained with respect to the annealing temperature. [ABSTRACT FROM AUTHOR]