Understanding has advanced significantly in the interpretation of the thermal release of self interstitials into a silicon lattice from a region, e.g. ion implanted, which is rich in point defects. Progress has been accelerated through the use of delta doped layer structures, especially of boron doping type, where the transient enhanced diffusion (TED) of the dopant marks the arrival of the self interstitial species from a physically separate damage region. Frequently observed in such TED experiments is an immobile, electrically inactive, boron peak on top of the spreading diffusion profile. This signature boron peak has been attributed to the Si-interstitial driven clustering of boron. It has been observed that this feature occurs for high boron concentrations and implant fluences; however, a complete understanding of the clustering mechanism has remained elusive.
We present new data from experiments where the self implant fluence has been varied to allow the intensity of the transient flux to be adjusted and where repeat distances in the MBE structure have been adjusted to test for trapping. This has led to some clarifications to the current picture of boron clustering during TED. These results seem to be important in the context of the search for engineering control over dopant redistribution in Si during post-implantation annealing.