Solar cell radiation damage

During the past 34 years, silicon or gallium arsenide solar cells have remained the main power source for nearly all spacecraft; power output levels having risen from a few milliwatts (Vanguard 1, 1958) to many kilowatts in the 1970s and 1980s (Skylab, 21 kW; MIR, 10 kW; Hubble Space Telescope, 5 kW). The steady technological progress made in improving solar cell efficiency and, in particular, radiation resistance, has ensured that solar cells remain in the forefront and a ''moving target'' for competing technologies such as nuclear and thermodynamic systems. The radiation performance degradation characteristics of currently produced solar cells and some results of associated deep level transient spectroscopy (DLTS), carrier lifetime measurements and isochronal annealing experiments are described herein. (author)