The study presents detailed isothermal and isochronal annealing recovery of photovoltaic parameters in n+/p InGaP solar cells after 1MeV electron irradiation. Correlation of the solar cells characteristics with changes in the deep level transient spectroscopy data observed in irradiated and annealed n+/p InGaP diodes and solar cells showed that the H2 (Ev + 0.50eV) and H3 (Ev + 0.76eV) defects have a dominant role in governing the minority-carrier lifetime as well as carrier removal. However, capacitance–voltage measurements indicate that other defects must also play a role in the carrier removal process. In addition, the concentration of the H2 defect was found to decay significantly as a result of room temperature storage for 40 days, suggesting that InGaP-based solar cells will display superior radiation tolerance in space. Finally, the deep donor-like-defect H2 was tentatively identified as a P Frenkel pair.

Thermal Annealing Study of 1MeV Electron-Irradiation-Induced Defects in n+p InGaP Diodes and Solar Cells. A.Khan, M.Yamaguchi, J.C.Bourgoin, T.Takamoto: Journal of Applied Physics, 2002, 91[4], 2391-7