In silicon bicrystals grain boundaries (GBs) become recombining after they have been annealed in argon at temperatures higher than 800°C for tens of hours. In order to verify the eventual influence of metallic elements, interstitials gold atoms are introduced in the bicrystals by diffusion (T ≤ 8000 C) from gold dots deposited far from the GB (gold could be segregated by the GB but cannot give deep levels in the grains). It is found by DLTS, EBIC contrast and LBIC scan map that the recombination strength of GBs is not changed by gold in diffusion in as grown bicrystals, while it is reduced in annealed samples. Similar results are obtained with GBs of polycrystalline wafers.
It is concluded that the activation of GBs in CZ silicon bicrystals is certainly due to the segregation of a slow diffuser like oxygen, and that fast diffusers play a secondary role only.