A statistical analysis of the effect of PECVD deposition parameters on surface and bulk recombination in silicon solar cells

We have performed a statistically designed multiparameter experiment using response surface methodology to determine the optimum deposition and anneal conditions for PECVD silicon-oxide and silicon-nitride films on Si solar cells. Our process includes a unique in situ hydrogen plasma treatment to promote bulk defect passivation independently of surface effects. Our goal has been to define a process to optimize cell performance by minimizing recombination while also providing an effective antireflection coating. Our initial results show that excellent emitter-surface passivation, approaching that of the best thermally grown oxides, can be obtained using a single-layer nitride coating whose refractive index is optimized for antireflection purposes. Use of the PECVD-nitride instead of a TiO{sub 2} ARC resulted in an 11% increase in output power

Cytotoxicity effects of metal oxide nanoparticles in human tumor cell lines

Metallic and metal oxide nanoparticles (Nps) have a wide range of applications in various settings including household, cosmetics and chemical industries, as well as for coatings. Nevertheless, an in-depth study of the potential toxic effects of these Nps is still needed, in order to fulfill the mandatory requirement of ensuring the safety of workers, patients and the general public. In this study, Quick Cell colorimetric assays were used to evaluate the in vitro toxicity of different metal oxide Nps [Fe(II,III)Ox, TiOx, ZnO and CeO2] in several cell lines. The ZnO Nps were found to be highly toxic, with a lethal dose ≥100 μg/ml for all the cell lines studied. Western blot was also used to test the ability of the different Nps to activate the complement pathway. However, no activation of this cascade was observed when the Nps were added. In addition, the aggregation state and charge of the Nps in culture media was studied by dynamic light scattering (DLS) and measurement of zeta potential. Transmission Electron Microscopy was used to analyze Np uptake and localization at the cellular level

Construction of the LISA back-side fibre link interferometer prototype

The Laser Interferometer Space Antenna (LISA) is a joint ESA NASA mission to be launched in 2018. It is an interferometric gravitational wave detector with a measurement band going from 0.1 mHz to 1 Hz. The conceptual interferometer design is unique and includes many challenging aspects that must be analysed in terms of their stability in advance to the mission. One of these new features is the so-called back-side fibre link, which connects the two optical benches on-board each spacecraft. In its optical fibre, two frequency shifted laser beams are counter-propagating. LISA will only reach its design sensitivity, if these two beams inside this fibre experience the same pathlength changes down to a level of approximately 1 pm/\sqrt{\rm Hz} in the mHz range. In this paper, we present the construction of a quasi-monolithic interferometer that represents a cutout of the LISA interferometry concerning the back-side fibre link. In order to ensure a high thermal and mechanical stability of the interferometer, the hydroxide-catalysis bonding technique was applied. For the construction of the interferometer, a number of new alignment techniques and solutions were developed that are suitable for LISA prototype experiments

Optical bench development for LISA

For observation of gravitational waves at frequencies between 30 μHz and 1 Hz, the LISA mission will be implemented in a triangular constellation of three identical spacecraft, which are mutually linked by laser interferometry in an active transponder scheme over a 5 million kilometer arm length. On the end point of each laser link, remote and local beam metrology with respect to inertial proof masses inside the spacecraft is realized by the LISA Optical Bench. It implements further- more various ancillary functions such as point-ahead correction, acquisition sensing, transmit beam conditioning, and laser redundancy switching. A comprehensive design of the Optical Bench has been developed, which includes all of the above mentioned functions and at the same time ensures manufacturability on the basis of hydroxide catalysis bonding, an ultrastable integration technology already perfected in the context of LISA's technology demonstrator mission LISA Pathfinder. Essential elements of this design have been validated by dedicated pre-investigations. These include the demonstration of polarizing heterodyne interferometry at the required Picometer and Nanoradian performance levels, the investigation of potential non-reciprocal noise sources in the so-called backlink fiber, as well as the development of a laser redundancy switch breadboard

Testing the GRACE follow-on triple mirror assembly

We report on the successful testing of the GRACE follow-on triple mirror assembly (TMA) prototype. This component serves to route the laser beam in a proposed follow-on mission to the Gravity Recovery and Climate Explorer (GRACE) mission, containing an optical instrument for space-based distance measurement between satellites. As part of this, the TMA has to meet a set of stringent requirements on both the optical and mechanical properties. The purpose of the TMA prototype testing is to establish the feasibility of the design, materials choice and fabrication techniques. Here we report on co-alignment testing of this device to the arc second (5 μrad) level and thermal alignment stability testing to 1 μ rad {{K}-1}

The effect of hydrogen-plasma and PECVD-nitride deposition on bulk and surface passivation in string-ribbon silicon solar cells

We have investigated whether an in-situ hydrogen or ammonia rf-plasma treatment prior to a PECVD-nitride deposition would promote bulk defect passivation independently of surface effects. We also studied whether the predeposition of a thin silicon-nitride protective layer vbefore performing the plasma treatment would serve to minimize surface damage. We found that for the limited set of deposition conditions in of cells processed using the used five different deposition strategies and compared the resulting cell performance with that investigated so far, the direct deposition of PECVD-nitride produces the best cells on String Ribbon silicon wafers to date, with efficiencies up to 14.5%. Hydrogen and ammonia plasma pretreatments without a protective nitride layer resulted in better bulk passivation, but damaged surfaces. Pretreatments after deposition of the protective layer produced the best surface passivation, but were not effective in passivating the bulk

Cytotoxicity effects of metal oxide nanoparticles in human tumor cell lines

Metallic and metal oxide nanoparticles (Nps) have a wide range of applications in various settings including household, cosmetics and chemical industries, as well as for coatings. Nevertheless, an in-depth study of the potential toxic effects of these Nps is still needed, in order to fulfill the mandatory requirement of ensuring the safety of workers, patients and the general public. In this study, Quick Cell colorimetric assays were used to evaluate the in vitro toxicity of different metal oxide Nps [Fe(II,III)Ox, TiOx, ZnO and CeO2] in several cell lines. The ZnO Nps were found to be highly toxic, with a lethal dose ≥100 μg/ml for all the cell lines studied. Western blot was also used to test the ability of the different Nps to activate the complement pathway. However, no activation of this cascade was observed when the Nps were added. In addition, the aggregation state and charge of the Nps in culture media was studied by dynamic light scattering (DLS) and measurement of zeta potential. Transmission Electron Microscopy was used to analyze Np uptake and localization at the cellular level