EVIDENCE OF AN IMPROVED VOLTAGE PERFORMANCE OF A NEW TYPE OF TRIPLE JUNCTIONSOLAR CELL FOR SPACE

摘要

A new type of triple junction solar cell for space applications (named TJH cell), , has been recentlydeveloped. The structure has an InGaP top cell, an InGaAs middle cell and a Ge bottom cell obtained by Zn diffusionfrom a AlGaAs window and nucleation layer into the Ge substrate. This type of cell has a P on N polarity and it isstill in development. Conversion efficiencies in the range of 24-25% have been obtained, measured by NASA LearJet and SPASOLAB. This paper describes the new cell structure and the results of testing with 1 MeV electrons up toa fluence of 1.1015 15 e-/cm2 and with 5, 7, and 10 MeV protons up to a fluence of 5.1012 12 p+/cm2 (including omni–directional fluences). All the sub-cells, top, middle and bottom (with polarity P on N and N on P), have beenseparately irradiated with electrons to distinguish the different rates of the degradation. The proton irradiation hasbeen carried out on the full TJH cell. The paper is also comparing the degradation curves of the TJH cell with thepresent state of the art.