Delay of Regeneration by Adding Aluminum in Boron-Doped Crystalline Si
Here, two B-doped Cz-grown Si materials with different Al concentrations are investigated concerning the long-term behavior of excess charge carrier lifetime under injection at elevated temperature. By determining the defect density and the surface saturation current density, a delay in regeneration and a delay in the onset of surface-related degradation is found in the material containing an order of magnitude more Al. Investigations under constant excess carrier concentration reveal that the effect of the delay is still significant, but less pronounced compared with constant generation conditions, so the effect causing the delay seems to be injection dependent. The findings can be explained by the higher activation energy for the splitting of Al−H pairs compared with splitting of B−H pairs, which might cause a delayed release in H from the dopant H configuration. Assuming that regeneration depends on this released H, the delay in regeneration can be explained by this model.