Effect of Hydrogen Gas Dilution on Sputtered Al:ZnO Film

AbstractAl doped zinc oxide (ZnO:Al) is a transparent and conductive oxide used as contact and antireflection layer in solar cell based on Si or chalcogenide. Generally it is grown by magnetron sputtering but the resistivity of our films grown with this technique are still in the order of 10-3Ωcm for layers grown at the temperatures used to produce the solar cells. The doping property of Hydrogen for Al:ZnO grown with two different sputtering techniques, DC magnetron sputtering and Pulsed magnetron sputtering at different growth parameters have been studied and the sample characterized optically, electrically and structurally. The best resistivity is 6.7*10-4Ωcm was obtained using Pulsed magnetron sputtering

Laser Treatment to form An Effective Base Contact in a - Si:H/c-Si Heterojunction Solar Cells☆

Abstract In this paper we investigate the p-type a-Si:H/ia-Si:H/p-type c-Si structure, commonly used as base contact in amorphous/crystalline silicon heterojunction solar cell when fabricated on p-type c-Si wafer. Even though the most effective amorphous silicon/crystalline silicon heterostructure is based on n-type c-Si due to higher bulk lifetime, the p-type c-Si still remains the most common and cheaper substrate for silicon based solar cell. In particular we study the effect of localized 532 nm pulsed laser treatment at different laser conditions in order to reduce the cell series resistance due to the base contact. In this approach the p-type a-Si:H layer is used as a source of boron dopant. Depending on the thickness of the p-type a-Si:H film, when the laser beam is focused on p-type a-Si:H layer the boron can be transferred into the c-Si base to form an overdoped region and then an effective local Back Surface Field, able to enhance the hole collection at the metal of the base electrode in the p-type c-Si based heterojunction solar cell. The application of a thin Aluminum layer on top of the amorphous silicon to be treated by laser is also concerned. Series resistance of a transverse structure composed by the laser treated p-type a-Si:H/c-Si/opposite surface contacted by InGa is considered to optimize the laser procedure. Values as low as 0.5 Ωcm 2 are obtained when the aluminum layer is adopted

Hydrogen Plasma and Thermal Annealing Treatments on a-Si:H Thin Film for c-Si Surface Passivation☆

Abstract High efficiency solar cells can be fruitfully built using the amorphous/crystalline silicon technology, taking advantage of the high V oc that occurs as a consequence of excellent c-Si surface passivation provided by a-Si:H films. Improvements of the interface quality can be obtained using post deposition treatments such as hydrogen plasma and thermal annealing. We propose the use of surface photovoltage technique, as a contact-less tool to evaluate the energetic distribution of the state density at amorphous/crystalline silicon interface, and FTIR spectroscopy of the same samples to appreciate the evolution of Si-H and Si-H 2 bonds. This approach leads to interesting applications for monitoring and improving the interface electronic quality, which is extremely susceptible to the different treatments adopted. We found that thermal annealing produces a metastable state which goes back to the initial state after just 48 hours, while the effect of hydrogen plasma post-treatment results more stable. Moreover H 2 plasma reduces the defect density of one order of magnitude with respect to thermal annealing and keeps it constant also after one month. The hydrogen plasma is able to reduce the defect density but at the same time increases the surface charge within the a-Si:H film due to the H + ions accumulated during the plasma exposure, leading to a more stable configuration

Fabrication of Cu2ZnSnS4 solar cells by sulfurization of evaporated precursors

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Are children with Specific Language Impairment competent with the pragmatics and logic of quantification?

Specific Language Impairment (SLI) is understood to be a disorder that predominantly affects phonology, morphosyntax and/or lexical semantics. There is little conclusive evidence on whether children with SLI are challenged with regard to Gricean pragmatic maxims and on whether children with SLI are competent with the logical meaning of quantifying expressions. We use the comprehension of statements quantified with ‘all’, ‘none’, ‘some’, ‘some…not’, ‘most’ and ‘not all’ as a paradigm to study whether Spanish-speaking children with SLI are competent with the pragmatic maxim of informativeness, as well as with the logical meaning of these expressions. Children with SLI performed more poorly than a group of age-matched typically-developing peers, and both groups performed more poorly with pragmatics than with logical meaning. Moreover, children with SLI were disproportionately challenged by pragmatic meaning compared to their age-matched peers. However, the performance of children with SLI was comparable to that of a group of younger language-matched typically-developing children. The findings document that children with SLI do face difficulties with employing the maxim of informativeness, as well as with understanding the logical meaning of quantifiers, but also that these difficulties are in keeping with their overall language difficulties rather than exceeding them. The implications of these findings for SLI, linguistic theory, and clinical practice are discussed

Dehnung und kristallene Defekte in den Epitaxial- GaN Schichten studierten durch hochauflösende Röntgenbeugung

The scope of this thesis is to study the strain state, dislocation densities and other microstructuralfeatures of GaN-based layers grown by metalorganic vapor phase epitaxy(MOVPE) on (0001) sapphire and (0001) 6H-SiC substrates using x-ray techniques

Strain and crystalline defects in epitaxial GaN layers studied by high-resolution X-ray diffraction

The scope of this thesis is to study the strain state, dislocation densities and other microstructuralfeatures of GaN-based layers grown by metalorganic vapor phase epitaxy(MOVPE) on (0001) sapphire and (0001) 6H-SiC substrates using x-ray techniques

A water cooled, high power, dielectric barrier discharge reactor for CO2 plasma dissociation and valorization studies

Abstract Aiming at the energy efficient use and valorization of carbon dioxide in the framework of decarbonization studies and hydrogen research, a novel dielectric barrier discharge (DBD) reactor has been designed, constructed and developed. This test rig with water cooled electrodes is capable of a plasma power tunable in a wide range from 20W to 2 kW per unit. The reactor was designed to be ready for catalysts and membrane integration aiming at a broad range plasma conditions and processes, including low to moderate high pressures (0.05–2 bar). In this paper, preliminary studies on the highly endothermic dissociation of CO2, into O2 and CO, in a pure, inert, and noble gas mixture flow are presented. These initial experiments were performed in a geometry with a 3 mm plasma gap in a chamber volume of 40cm3, where the process pressure was varied from few 200 mbar to 1 bar, using pure CO2, and diluted in N2. Initial results confirmed the well-known trade-off between conversion rate (up to 60%) and energy efficiency (up to 35%) into the dissociation products, as measured downstream of the reactor system. Improving conversion rate, energy efficiency and the trade-off curve can be further accomplished by tuning the plasma operating parameters (e.g. the gas flow and system geometry). It was found that the combination of a high-power, water-cooled plasma reactor, together with electronic and waveform diagnostic, optical emission and mass spectroscopies provides a convenient experimental framework for studies on the chemical storage of fast electric power transients and surges