the obtective of this program is to develop a vacuum die-casting process for producing silicon sheet suitable for photovoltaic cells and to develop production techniques for optimization of polycrystallie silicon solar cell output. efforts will examine process methods which are directed toward minimum cost processing of silicon into a quality suitable for producing solar cells with a terrestrial efficiency greater than 12 and having the potential to be scaled for large quantity production. in the vacuum die casting technique, silicon is melted under vacuum, and an evacuated die with a thin rectangular cavity is inserted into the melt. liquid silicon is then injected into the die using a positive pressure of an inert gas. the major portion of the die casting work will be performed at stanford research institute international under subcontract. the initial approach will follow parallel tracks: (1) obtain mechanical design parameters by using boron nitride, which has been shown to be non-wetting to silicon; (2) optimize silicon nitride material composition and coatings by sessile drop experiments; (3) test effectiveness of fluoride salt interfacial media with a graphite mold; and (4) test effect of surface finish using both boron nitride and graphite. having established the material and mechanical boundary conditions, a finalized version of the prototype assembly will be constructed and the casting varibles determined. polycrystalline silicon solar cells, with and without impurities, will be fabricated, characterized, and optimized at arcco solar. the major activities will fo