Structural changes in InP Si solar cells following irradiation with protons to very high fluences

Precisely how the short circuit current (J(SC)) is produced in a proton irr adiated n(+) p InP/Si solar cell at very high fluence levels has been deter mined from combined measurements of the cell structure using electrochemica l capacitance-voltage profiling and detailed analysis of the spectral quant um efficiency. Type conversion in the base region of the cell is shown to o ccur before an anomalous peak in the degradation curve for J(SC) is reached at high damage levels. The short circuit current, and hence the cell effic iency, ultimately collapse because the high absorption coefficient of InP e ventually prevents the generation of electron-hole pairs close enough to th e effective cell junction from being collected. (C) 1999 American Institute of Physics. [S0021-8979(99)08915-X].