57Fe charge states in MC-Si solar cells under light illumination after GeV-implantation of 57Mn

Immediately after the GeV-implantation of 57Mn nuclei produced by the RIKEN-RIBF facility, 57Mn/57Fe Mossbauer spectra in Si-solar cells are measured under light illumination. Comparing with the spectrum of p-type multi-crystalline-Si, the broad spectra of the solar cell under operation can be analyzed as a superposition of interstitial and substitutional Fe components with different charge states. The charge states of Fe impurities are created by the excess carrier injection followed by a directional carrier flow in the p-n junction. The present results provide us a possibility to clarify the carrier trapping process at the Fe impurities in Si-solar cells.