Screen printed In2O3-SnO2 nanocomposite: Structural and morphological properties and application for NO2 detection

In this work, we report on the sensing properties of screen-printed In2O3 (Indium Oxide) while adding a moderate quantity of SnO2. It was found that the addition of SnO2 improves the response and decreases the operating temperature of the sensitive element for NO2 detection. However, a non-controlled amount of SnO2 leads to opposite result; for this reason in the present investigation we test films with different composition in order to optimize the quantity of SnO2 to be added. The crystallinity, roughness and morphology of the obtained In2O3-SnO2 anocomposite were analyzed using X-ray Diffraction (XRD), Transmission Electronic Microscopy (TEM) and Atomic Force Microscopy (AFM). The atomic composition of the In2O3-SnO2 films was determined with the energy dispersive spectroscopy (EDX) analysis during TEM observations. The effect of the composition on the cristallinity and morphological properties of the films was analyzed. Finally, the In2O3-SnO2 films were tested like sensitive elements for NO2 detection, wherein the effect of the composition was correlated with the sensor response in NO2 ambient. It was found that the addition of a moderate quantity of SnO2 to In2O3 exhibited high sensitivity at rather lower operating temperatures

Structural and optical modeling of electro deposited CuInSe2 thin films

The ternary semiconductor CuInSe2 is one of the most advantageous materials for the manufacturing of thin film solar cells. In this study, CuInSe2 thin films were prepared at room temperature using the electrodepositing method. The as-prepared films were found to be amorphous. The CuInSe2 films were crystallized in a tubular resistive furnace, and characterized by means of the the X-ray diffraction (XRD) and UV-VIS-NIR spectroscopy techniques. The parameters to optimize are the temperature and duration of the annealing time, and the Cu/In ratio in the precursors

The use of chemical vapor etching in multicrystalline silicon solar cells

With the purpose to increase the light confinement and the efficiency of silicon solar cells, the reflection of the surface emitter needs to be minimized and the minority carrier collection improved. This improvement is currently achieved by the application of the chemical vapor etching (CVE) technique. In this paper, we investigate the effects of CVE on surface texturing and silicon grooving. CVE-based porous silicon (PS) was found to be a good antireflection and passivation layer for multicrystalline Si (mc-Si) solar cells. As a result, the reflectivity of the mc-Si solar cell decreases by about 60% of its initial value in the 650–950 nm spectral range and the internal quantum efficiency improves by 30% after PS application in the 400–700 nm spectral range. CVE can be used for surface texturing of single or mc-Si Si wafer leading to lower surface reflectivity and reduction of the dead layer. The chemical vapor etching techniques enabled realize buried metallic contacts by grooving mc-Si silicon wafers. The spectral response of mc-Si solar cells was found to enhance of about 12% in the long wavelength range when a rear buried metallic contacts is achieved, while a significant increase of about 35% was observed at short wavelengths (400–650 nm spectral range) subsequent front grid buried metallic contacts realization

Origin of the photoluminescence shifts in porous silicon

The origin of the photoluminescence (PL) shifts in Porous Silicon (PS) is discussed according to a quantum confinement – based model, in which we modelize the PS layer as a mixture of quantum dots and wires. It was shown that a PL blueshift or redshift may occur during laser irradiation of PS, depending on preparation conditions. No PL shift was observed for some PS samples, even after a long ageing in air, due to the presence of an amorphous silicon phase detected from Raman spectroscopy measurements. It was found that the presence of the amorphous phase plays an important role in the PL behaviour of oxidised PS