Hydrogenation of Si from SiNx(H) films: Characterization of H introduced into the Si

A promising method to introduce H into multicrystalline Si solar cells in order to passivate bulk defects is by the postdeposition annealing of a H-rich, SiNx surface layer. It has previously been difficult to characterize the small concentration of H that is introduced by this method. Infrared spectroscopy has been used together with marker impurities in the Si to determine the concentration and depth of H introduced into Si from an annealed SiNx film

Development of high efficiency solar cells on silicon web

Web base material is being improved with a goal toward obtaining solar cell efficiencies in excess of 18% (AM1). Carrier loss mechanisms in web silicon was investigated, techniques were developed to reduce carrier recombination in the web, and web cells were fabricated using effective surface passivation. The effect of stress on web cell performance was also investigated

Loss-of-function analysis of EphA receptors in retinotectal mapping

Peer reviewedPublisher PD

Directional solidification of aluminum-nickel eutectic alloys using electroslag remelting

Attempts were made to produce directionally solidified, specifically grain aligned Al-6 wt pct Ni eutectic alloy using a laboratory scale ESR unit. For this purpose sand cast alloy electrodes were electroslag remelted under different mold conditions. The grain structure of the ingots obtained from these meltings showed that insulated silica molds gave the best vertical alignment of grains along the length of the ingot. The NiAl3 fibers within the grains tended to fan out and there was only a preferred alignment of fibers along the growth direction under the conditions of our experiments. The ESR parameters most suitable for vertical alignment of eutectic grains have been identified. In some electroslag remelting trials ingots were grown on a seed ingot. This resulted in a fewer vertical grains compared to the case when no seed ingot was used. The sand cast specimen of the eutectic exhibited a maximum tensile strength of around 88.2 MN/m2 (9.0 kg/mm2) whereas conventional ESR using water cooled mold gave strength value of 98.0 MN/m2 (10 kg/mm2). The directionally solidified ESR material showed longitudinal tensile strength as high as 213.7 MN/m2 (21.8 kg/mm2) which could be further increased to 220.6 MN/m2 (22.5 kg/mm2) by using the seed ingot. The average growth rate was varied between 5 to 25 mm/min during electroslag remelting in this study. The flow stresses, tangent modulus and ultimate tensile strength of directionally solidified eutectic increased with increasing growth rates