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 irradiated n(+) p InP/Si solar cell at very high fluence levels has been determined from combined measurements of the cell structure using electrochemical capacitance-voltage profiling and detailed analysis of the spectral quantum efficiency. Type conversion in the base region of the cell is shown to occur 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 efficiency, ultimately collapse because the high absorption coefficient of InP eventually prevents the generation of electron-hole pairs close enough to the effective cell junction from being collected. (C) 1999 American Institute of Physics. [S0021-8979(99)08915-X].