Two major requirements for space solar cells are high efficiency and survivability in the naturally occurring charged particle space radiation environment. It was known that solar cell on p-type 10 Ωcm Si substrate has the best radiation resistance. In this study, we fabricated $n^+p$ solar cell using 10 Ωcm substrate and measured the characteristics. AR coating was designated for better conversion efficiency. AR $n^+p$ solar cell has better short-circuit current than $n^+p$ solar cell. Optimised $p^+$ layer was obtained through the numerical analysis, and we faricated AR $n^+pp^+$ solar cell, and considered the problem of the fabrication. To solve this problem, we reduced the thickness of the base and the increase of conversion efficiency was shown. Measuring the minority carrier diffusion length, the effect of the phosphorus gettering on the solar cell was investigated.
