Irradiation of Cu(In,Ga)Se/sub 2/ thin film solar cells with 110-, 210-, and 290- keV protons

This study presents irradiation experiments of Cu(In,Ga)Se/sub 2/ thin-film solar cells using protons with energies of 110, 210, and 290 keV, i.e., in an energy range that is expected to cause maximum damage in the Cu(In,Ga)Se/sub 2/ absorber layer. Monte-Carlo simulations predict the average depth of the irradiation induced vacancies as well as the integral number of generated vacancies. From our irradiation experiments, we find critical fluences, that causes an open circuit voltage losses /spl Delta/V/sub OC/ = 50 mV, of 1/spl times/10/sup 12/, 3/spl times/10/sup 11/, and 8/spl times/10/sup 11/ cm/sup -2/ for 110-, 210- and 290-keV protons. Quantum efficiency analysis of irradiated solar cells show collection losses in the whole wavelength range after 110-keV proton bombardments, whereas the losses shift to longer wavelengths with increasing proton energy and penetration depth. Our experiments, thus, indicate a highly localized damage in various depths of the Cu(In,Ga)Se/sub 2/ solar cells as predicted by the simulations.