Journal of New technology and Materials

Solar radiation incident on vertical and inclined surfaces consists of beam, sky diffuse and ground reflected components. The ground reflected component may be significant, particularly in the northern latitudes due to low elevations of the sun and, at times, due to the presence of highly reflecting snow cover. Accurate estimation of ground reflected radiation would require knowledge of the foreground type and geometry, its reflectivity and the condition of the sky. The electrical current generated by the solar cells is very sensitive to the incident spectral distribution and intensity. This distribution varies greatly during the day due to changes in the sun’s position or weather conditions. This work investigates the feasibility of using a solar spectral radiation model SMARTS2 to estimate the global solar irradiance on two different sites in Algeria (Setif and Bejaia) and assess the influence of varying ground albedo on the conversion efficiency of GaInP and amorphous (a-Si : H) solar cells. The results show an augmentation in the short circuit current of amorphous (a-Si : H) solar cell due to increasing albedo. It is 6.25% and 9.84% under global radiation and for Setif and Bejaia sites respectively. However for GaInP solar cell, the augmentation of the short circuit current is 6.97% and 10.93% for Setif and Bejaia sites respectively. Nevertheless, the efficiency increases with increasing albedo for GaInP and amorphous (a-Si : H) solar cells.

Thin film solar cells based on Cu2ZnSnS4 (CZTS) absorbers are proposed with the structure glass/Mo/CZTS/buffer/ZnO. In this work we have simulated CZTS thin film solar cell using solar cell capacitance simulator (SCAPS). The influences of thickness of (CZTS) absorber, thickness of (CdS) buffer layer and Zinc oxide window Layer (ZnO) on the photovoltaic cell parameters are studied. It can be seen after reviewing the results, that for high conversion efficiency, the cell should have a thin buffer layer and a thick absorber layer. In addition, the effect of operating temperature on the cell performance shows that the efficiency will be strongly affected by the increased temperature.

ZnO nanoparticles with different grain sizes have been obtained by mechanical milling, after different treatment times : 3, 6, 12and 24 hours.
The final products have been characterized by different analytical techniques, such as X Ray Diffraction, Photoluminescence,Fourier transform infrared (FTIR) and UV-Visible spectroscopies.The cytotoxic effect of one selected concentration ZnO nanoparticles have been evaluated for paramecium growth kinetics and the mortality rate have been recorded as a function of time.Findings demonstrated that the evolution of the paramecium cell number is clearly affected by ZnO Nps presence.

Zinc oxide (ZnO) nanostructures were electrodeposited onto ITO coated glass substrates from nitrate medium at different temperatures. The electrochemical deposition process was analyzed and the characteristics of the nanostructures were discussed. The electrochemical results showed that the deposition temperature had an important effect on the current density and the film morphology. From the Mott-Schottky measurements, the flat-band potential and the donor density for the ZnO
nanostructure are determined. The morphological, structural and optical properties were studied by scanning electron microscopy (SEM), x-ray diffraction techniques (XRD) and spectrophotometer in the ultraviolet UV–visible region. SEM images demonstrated that the morphology of ZnO nanostructures depend greatly on the bath temperature. The XRD patterns revealed the formation of phase-pure ZnO nanostructure with hexagonal wurtzite phase. The optical transmittance spectrum gave a high transmittance of 82 % at low temperatures, and the optical band-gap (Eg) of the ZnO nanostructures was between 3.253.49 eV.

In this work, the thermal buckling properties of carbon nanotube with small scale effect are studied. Based on the nonlocal continuum theory and the Timoshenko beam model, the governing equation is derived and the critical buckling temperature is presented. The influences of the scale coefficients, the ratio of the length to the diameter, the transverse shear deformation and rotary inertia are discussed. It can be observed that the small scale effects are significant and should be considered for thermal analysis of carbon nanotube. The critical buckling temperature becomes higher with the ratio of length to the diameter increasing. Furthermore, for smaller ratios of the length to the diameter and higher mode numbers, the transverse shear deformation and rotary inertia have remarkable influences on the thermal buckling behaviors.

Perpendicular Silicon nanowires (SiNWs), having 20 micrometer in length, were fabricated by metal assisted chemical etching of n-type Si(100) wafers in aqueous HF-solution. In a second step, NiFe films were electrodeposited onto theses SiNWs. The structure and magnetic properties of as deposited NiFe layers were studied by X ray diffraction (XRD) and vibrating sample magnetometer (VSM). From X-ray diffraction, the FCC NiFe structure was evidenced with a lattice constant, a, equal to 3.5270 Å. From hysteresis curves, we compute the coercive field, Hc, values. We found that the Hc // values range from 102 Oe to 236 Oe.

The demand of miniature electronic systems has been increasing for several decades. The physical size of systems is reduced due to advancements in integrated circuits. With reduction in size of electronic systems, there is also an increasing demand of small and low cost antennas. Patch antennas are one of the most attractive antennas for integrated RF systems due to their compatibility with microwave integrated circuits. In this paper, the effects of substrate dielectric constant and particularly the miniaturization of the antenna size on the return loss characteristics of patch micro strip antenna (MSPA) have been investigated using the wave concept iterative procedure (WCIP) method. Accuracy of the present results is compared with previous work which has been done theoretically and experimentally.

In this work, we are interested in thin films of zinc oxide doped with nickel (Ni), deposited on glass substrates and elaborated by the sol-gel dip coating technique. The effects of the doping concentration in the range of outlet (1%, 3% and 5at%) have been thoroughly studied. The morphological properties of ZnO-Ni films were studied by Atomic Force Microscopy (AFM). The optical properties of the ZnO:Ni thin films were examined by UV-visible spectroscopy and the Tauc method was used to estimate the optical band gap and hall effect for electrical characteristique. Atomic Force Microscopy has indicated that the surface of the ZnO:Ni thin films have uniform and dense ZnO grains. The optical transmittance of ZnO:Ni thin films increased from 86 to about 93% from pure ZnO films to ZnO film doped with 3 wt% Ni and then decreased for 5 wt% Ni, and the optical band gap from 3.297 eV to 3.23eV. The electrical characterization performed using the technique of hall effect, gave a maximum electrical conductivity of 9.3 10-3(Ω.Cm)-1 obtained for the film doped with 3%Ni.

In this study, Al-doped zinc oxide (AZO) nanostructures are prepared on polycrystalline fluorine-doped tin oxide (FTO)-coated conducting glass substrates from nitrates baths by the electrodeposition process at 70 °C. The electrochemical, morphological, structural and optical properties of the AZO nanostructures were investigated in terms of different Al concentration in the starting solution. It was found from the Mott–Schottky (M-S) plot that the carrier density of AZO nanostructures varied between 3.111020 to 5.561020 cm-3 when the Al concentration was between 0 and 5 mM. Atomic force microscopie (FM) images reveal that the concentration of Al has a very significant influence on the surface morphology and roughness of AZO thin films. X-ray diffraction (XRD) patterns demonstrate preferential (002) crystallographic orientation having c-axis perpendicular to the surface of the substrate and average crystallites size of the films was about 23–36 nm. As compared to pure ZnO, Al-doped ZnO exhibited lower crystallinity and there is a shift in the (002) diffraction peak to higher angles. ZnO nanostructures were found to be highly transparent and had an average transmittance of 80 % in the visible range of the spectrum. After the incorporation of Al content into ZnO the average transmittance increased and the band-gap tuning was also achieved (from 3.22 to 3.47 eV).

In this work, the effect of the radiation on the current-voltage characteristics of device GaAs metal Schottky field effect transistors (MESFET) at room temperature is investigated. Numerical Simulation tuned by means of a physics based device simulator. When the substrate of this transistor is subjected to radiations, structural defects, which are created, have undesirable effects and can degrade the performance of the transistors. These defects appear like deep traps. Results showed that in the presence of donor traps the current-voltage characteristics increases. However, acceptor traps have a significant effect on the current-voltage characteristics. In the presence of acceptor traps, the space charge zone in the channel increases, hence, reduces the current drain.