Radiation-induced carbon-related defects in p-type silicon

Abstract

The production and removal of carbon-related defects have been investigated in 1-MeV electron-irradiated boron-doped silicon solar cells using deep level transient spectroscopy (DLTS). In Czochralski (CZ) material, the interstitial carbon defect (hole trap at Ev+0.27 eV), CI, decays by thermal and charge injection processes. We find that irradiation by MeV electrons creates CI while simultaneously removing it through the minority-carrier injection process. Removal of CI correlates with significant growth in the density of a complex reportedly consisting of carbon and oxygen (hole trap at Ev+0.38 eV). Thermal annealing produces a different DLTS signal than does minority-carrier injection indicating that the carbon and oxygen complex (C+O) is at least two species. The effective cross section for minority-carrier-induced annealing of CI is found to be 2×10−18 cm2 in these samples.