Kevin.Dowling%CMU-RI-ROVER@sri-unix.UUCP (11/10/83)
Reported in latest Laser Focus and EOSD: Spire Corp. has developed a process for growing a thin film of Ga-As directly on a silicon substrate. The process converts a conventional single band-gap Si cell with a typical efficiency of 12% to a two band-gap cell with a theoretical efficiency of 30% and a likelyconversion rate of 25% in large scale production. In solar cell application, Si is lower in cost but GaAs is more efficient because it captures a larger portion of the solar spectrum. The blurb (in the postdeadline reports section) goes on to mention that the method is a metalorganic chemical vapor process that allow extremely precise deposition of the GaAs. At a production level of 1MW per year, this photovoltaic process is estimated to add $1.30/W to cell costs; at 50MW/year, only $0.22/W. Cell effficiency will thus be more than doubled.