We welcome suggestions for topics and content. Previous Issues are available. The ALS is now accepting proposals from scientists who wish to conduct research at the facility as independent investigators during April-September 1998. The deadline for proposals is January 15, 1998. Information on the proposal process is available at the same location.
Solar energy offers promise for environmental reasons and as a power source for remote locations.
Scott McHugo, investigating this problem at Beamline 10.3.1, has characterized how copper and nickel contaminants cluster in silicon and observed their partial disappearance under thermal treatment. When a solar cell absorbs sunlight, extra electrons and holes are created on both sides of the p-n junctions. A reduction in this electrical current, and thus in the solar cell's efficiency, occurs when minority carriers recombine with majority carriers before reaching a junction. The distance the carriers travel before recombination is called diffusion length. Metal contaminants decrease diffusion length, so it is essential to remove them.