Dual N/Pb ion-implanted Si: Temperature dependence of the novel shift of the Pb peak under electron beam annealing

(100) Si was dual ion-implanted with 24 key N and 7 key Pb to peak concentrations similar to 10 at.%. Implanted samples were then electron beam annealed (EBA) at a peak temperature T for 30 s with T ranging from 100 degrees C to 900 degrees C and for 15 s at 1000 degrees C. Pb profiles were measured using RBS and surfaces characterised by AFM. For T up to 500 degrees C there was no shift in the profile from the implanted depth similar to 10 nm. For higher values of T a striking feature was the large movement of the Pb profile away from the surface without a significant change in width or Pb content. The profile depths were: similar to 40 nm for 600 degrees C, similar to 68 nm for 700-900 degrees C and similar to 80 nm for 1000 degrees C. The response to EBA was found to be strongly dependent on both ion implantation order and Si starting structure. For (1 0 0)Si nanowhiskers formed on the treated surfaces for T=900 degrees C and 1000 degrees C. A model is developed based on the restructuring of the amorphous implanted layer under EBA. It is proposed that a compaction starting at the surface sweeps the Pb before it via a stress interaction as it advances into the Si. (c) 2011 Elsevier B.V. All rights reserved.