Imaging and modelling the internal gettering of interstitial iron by grain boundaries in multicrystalline silicon

In this paper a simple one-dimensional diffusion-capture model is used to effectively characterise the reduction in interstitial Fe concentrations near grain boundaries in multicrystalline silicon by two fitting parameters: the diffusion length of Fe atoms and the gettering velocity at the grain boundary. The measurements are achieved by photoluminescence images taken before and after dissociating FeB pairs in silicon. The measurement artefacts of lateral photon scattering and lateral carrier diffusion are discussed. The method and the model are verified by a multicrystalline silicon wafer annealed at low temperatures which are known to result in diffusion-limited internal gettering of interstitial Fe.