243 research outputs found
The occurrence of selected chemical pollutants (Simazine, Lindane and Permethrin) in river fish. Progress Report December 1991
The occurrence of selected chemical pollutants (Simazine, Lindane and Permethrin) in river fish. Progress Report of first year's work July 1992
An experimental treatment of Simulium posticatum with Bti at selected sites on the River Stour, Dorset, 1992
High-efficiency, radiation-resistant GaAs space cells
Although many GaAs solar cells are intended for space applicatons, few measurements of cell degradation after radiation are available, particularly for cells with efficiencies exceeding 20 percent (one-sun, AMO). Often the cell performance is optimized for the highest beginning-of-life (BOL) efficiency, despite the unknown effect of such design on end-of-life (EOL) efficiencies. The results of a study of the radiation effects on p-n GaAs cells are presented. The EOL efficiency of GaAs space cell can be increased by adjusting materials growth parameters, resulting in a demonstration of 16 percent EOL efficiency at one-sun, AMO. Reducing base doping levels to below 3 x 10(exp 17)/cu m and decreasing emitter thickness to 0.3 to 0.5 micron for p-n cells led to significant improvements in radiation hardness as measured by EOL/BOL efficiency ratios for irradiation of 10(exp -15)/sq cm electrons at 1 MeV. BOL efficiency was not affected by changes in emitter thickness but did improve with lower base doping
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