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The performance of copper indium gallium selenium (CIGS) based solar cells with cadmium sulfide (CdS) and magnesium zinc oxide (MgxZn1-xO) buffer layers has been investigated comparatively with the new version of a one-dimensional device simulation program for the analysis of microelectronic and photonic structures (wxAMPS-1D). The structures of solar cells have been analysed keeping in view the effect of doping as well as of thickness of buffer and absorber layers. It is observed that the conversion efficiency and external quantum efficiency (EQE) are improved using Mg0.125Zn0.875O compound buffer layer for ZnO/Mg0.125Zn0.875O/CIGS structure to 22.01% and 89.7%, respectively, whereas the obtained conversion efficiency and EQE for ZnO/CdS/CIGS structure are 21.06% and 88.78%, respectively. The obtained results are in good agreement with the recently published work and the proposed structure of solar cells would have potential regarding improvements in the existing solar cell technology. [ABSTRACT FROM AUTHOR]

The development of SAC-OCDMA system is based on the creation of new code structure. A novel proposed code structure is called ZFD that is based on the combination of various matrix creation methods and especially on the factorial function. This approach has not been exploited before in the OCDMA system. This novel code has its own advantage that represented in its possibility to generate code-words in flexible way by setting variable basic codes at fixed code weight. The performance of this proposed code is demonstrated via mathematical methods. It is represented by its optimal cross-correlation to avoid the multiple access interference (MAI). Consequently, the effects of the contributed noises using direct detection method have been considered. These noises are represented by shot noise and thermal noise. In addition, a system of three users was simulated with ZFD code under the C band (1530–1565 nm) for the upstream signal with different channel spacing (0.8, 1 and 1.2 nm). In this paper, several parameter effects such as fiber length, effective source power and data rate have been studied and compared to prove the effectiveness of this code. Also, ZFD code has been compared to some other codes such as RD, EDW and MDW according to the previous parameters. The suggested code has reached good results in terms of the bit error rate (BER) and the eye diagram. [ABSTRACT FROM AUTHOR]

In this article, an experimental system based on the Quadruple Pass Double Stage with a tunable pass filter configuration, is used to amplify the output signal of the Erbium-doped fiber amplification and eliminate the noise due to the amplified spontaneous emission backwards. The pumping power of the second stage is set at 220 mW, and the input power at −50 dBm, a maximum gain of 68 dB at a minimum noise threshold is achieved. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) is a very successful technique to calculating the properties of manyelectron systems from first principles. The bands structures, charge density and density of state (DOS) of monoclinic HfO2 are calculated using Pseudo potential (PP) and Atomic Orbitals (AO) method, within the density functional theory DFT, generalized gradient approximation GGA and local density approximation LDA. Hafnium oxide (HfO2) is a high-k dielectric (dielectric constant k ~ 25 at 300 K, band gap Eg ≈ 6 eV); thermally stable up to 700 °C. HfO2 is used in semiconductor manufacturing processes where they are usually used to replace a silicon dioxide gate dielectric. [ABSTRACT FROM AUTHOR]

Total or partial shading conditions have a significant impact rate on the capability of delivering energy, in addition to the on-site environmental condition which effects the PV module output production. Generally, the shading effect is caused by the PV generator inter-row configurations, cloudy perturbations, the buildings and trees. In this paper, an investigation study has been carried out by testing different PV module types (mono-crystalline, polycrystalline) under different shading rates. The obtained IV characteristics have been treated through the Bishop model where the power losses occurred on the PV module output, have been evaluated. The measured and estimated I-V characteristic plots illustrated a good agreement and the used model provides an accurate power losses prediction caused by different shading effects, even in desert areas. [ABSTRACT FROM AUTHOR]