Radiation and flight testing of ITO/InP solar cells

Several studies have demonstrated that indium-phosphide-based cells have a strong potential for space applications, due to their radiation resistance. Proton irradiation studies on ITO/InP cells in the 2-50 MeV range are summarized, and the results are compared with data for silicon and gallium arsenide cells. Emphasis is placed on flight data for ITO/InP cells from the LIPS III flight experiment. Data are presented for a period of almost two and a half years in orbit and compared to data for silicon cells on the same experimental panel. The ITO/InP cells show interesting variations in short-circuit current, which are also observed for silicon cells on the same panel and are clearly the result of some external influence. Major temperature errors have been discounted since. in this case, a large variation in open-circuit voltage would be expected, and this was not observed. Despite these variations, the data for the entire period so far received agree well with the base values calculated from the data for the first 100 days of the experiment. Thus, there is no evidence of current degradation in the ITO/InP cells to date. The silicon cells, by contrast. show a clear degradation over the course of the mission