Improved performance of p/n InP solar cells

The high electrical conversion performance and radiation resistance of InP solar cells were discovered during the last decade. The combination of these two characteristics make InP a very attractive material for space solar cells. To date, the best performance results for both homo-epitaxial and hetero-epitaxial InP solar cells were achieved using a n/p configuration. The p/n configuration is desirable for hetero-epitaxial growth on inexpensive, strong, light weight, group IV substrates such as Si and Ge. We have succeeded in developing p/n configuration homo-epitaxy InP solar cells with begining-of-life AM0 efficiency values exceeding 17.6%. The high efficiency values resulted from improved emitter performance due to a reduction of Zn interstitial defects in the p-type emitter. Preliminary 3 MeV proton irradiation resistance data are presented which show the high efficiency p/n cells retain 75% of begining-of-life power after 7/spl times/10/sup 11/ protons/cm/sup 2/ fluence.