Radiation-hard, high efficiency InP solar cell and panel development

Indium phosphide solar cells with efficiencies over 19% (Air mass zero, 25 degrees C) and area of 4 cm2 have been made and incorporated into prototype panels. The panels will be tested in space to confirm the high radiation resistance expected from InP solar cells, which makes the material attractive for space use, particularly in high-radiation orbits. Laboratory testing indicated an end-of-life efficiency of 15.5% after 1015 1 MeV electrons, and 12% after 1016. These cells are made by metalorganic chemical vapor deposition, and have a shallow homojunction structure. The manufacturing process is amendable to scale-up to larger volumes; more than 200 cells were produced in the laboratory operation. Cell performance, radiation degradation, annealing behavior, and results of deep level transient spectroscopy studies are presented in this paper