Essential Research Incorporated proposes the development of a high efficiency, metamorphic triplejunction, III-V, space solar cell that will also have significantly higher radiation tolerance. The AM0 one sun efficiency of this AlGaInP/InGaAsP/InGaAs cell will be 31.7%, compared to 28% for the state-of-the-art InGaP/GaAs/Ge cell. Since most of the radiation damage in these cells can be attributed to the InGaAs or the GaAs cell, we propose to improve the radiation tolerance of the proposed cell in Phase I. Our modeling has shown that through a combination of cell thinning, dopant grading, and application of a reflecting layer on the back surface to force a second pass of the radiation through the cell, the EOL efficiency degradation of the InGaAs cell can be reduced from 20% to 5%. The Phase I proposal describes in detail, the innovative procedure that will be used to achieve this goal
