Radiation damage of 1.93-eV Al/sub 0.37/Ga/sub 0.63/As and GaAs solar cells grown by metalorganic chemical vapor deposition

The effects of radiation upon the solar cell performance of GaAs and 1.93-eV Al/sub 0.37/Ga/sub 0.63/As have been examined. GaAs cells having beginning-of-life efficiencies in excess of 20% (one-sun, AMO) in both the n-p and p-n configurations have been exposed to 1-MeV electrons. The p-n configuration showed better radiation tolerance than the n-p. The 1.93-eV Al/sub 0.37/Ga/sub 0.63/As material was studied both in n-p solar cells and in time-of-flight (TOF) samples, from which fundamental material parameters could be determined. The Al/sub 0.37/Ga/sub 0.63/As cells showed better radiation tolerance than their GaAs counterparts, and the diffusion length damage coefficient κ/sub L/ was measured to be --10/sup -8/. The observed damage cannot be satisfactorily explained using a model based solely upon the decrease in the bulk minority carrier lifetime. The effects of proton irradiation on the Al/sub 0.37/Ga/sub 0.63/As cells are also presented