NIEL DOSE Analysis on Triple Junction Cells 30% Efficient and Related Single Junctions

Space solar cells radiation hardness is of fundamental importance in view of the future missions towards harsh radiation environment (like the Jupiter missions) and for the new spacecraft using Electrical Propulsion. In this paper we report the radiation data for triple junction (TJ) solar cells and related component cells. Triple junction solar cell, InGaP top cell and GaAs middle cell degrade after electron radiation as expected. With proton irradiation, it was observed a high spread in the remaining factors, especially for the TJ and bottom cells. Very surprising was the germanium bottom junction that showed very high degradation after protons whereas it is quite stable against electrons. Radiation results have been analyzed by means of the Displacement Damage Dose method.