Analysis of the anomalous spectral response of InP solar cells induced by high fluence proton irradiation

Proton irradiation damage of InP n(+)-p space solar cells has been examined over a wide range of energy (0.015-10 MeV) and at high fluence (similar to 10(13) cm(-2)). Although the usual red spectral response degradation of InP cells has been observed under lower fluence proton irradiation, radiation testing has revealed an anomalous spectral response in the blue part of the spectrum. We propose a model to explain this phenomenon by considering conductivity-type conversion from p-InP into n-InP in a defect-induced region, determined by the proton range, of the p-InP base layer due to high fluence proton irradiation. This is confirmed by measurements of conductivity-type conversion of I?-InP crystals by high fluence (greater than or equal to 10(16) cm(-2)) 1 MeV electron irradiation. (C) 1997 American Institute of Physics.