Atomic-scale study of the role of carbon on boron clustering

Boron (BF₂, 20 keV, 3.14/cm²) and carbon (13 keV, 10¹⁵/cm²) implanted silicon annealed at 800 °C during 30 min or at 1000 °C during 10 s has been investigated using a laser-assisted wide-angle tomographic atom probe (LaWaTAP) instrument. Boron-silicon clusters containing ~ 1.3 at.% of boron atoms have been observed in boron implanted silicon with a concentration exceeding the solubility limit. Often identified as BICs, they are interpreted as a metastable phase. Furthermore, addition of carbon clearly reduced the clustering of boron. This was interpreted as a diminution of boron diffusion or as an increase of the solubility limit of boron. Carbon-silicon clusters containing ~ 1.5 at.% of carbon atoms were observed, maybe the precursors of the SiC phase.