Strong Diffusion Suppression of Low Energy-Implanted Phosphorous in Germanium by N2 Co-Implantation

In this work an effective diffusion suppression of low energy – high dose (11 keV, 1E15 cm−2) phosphorous in 10 keV/5 × 1E14cm−2 N2+ -implanted p- germanium is demonstrated. Diffusion of both species after isochronal 30 sec RTA annealing at 550–650◦C has been studied by SIMS in the presence of Al2O3 as surface capping layer. Nitrogen shows anomalous non-Fickian diffusion towards the Al2O3/Ge interface, while phosphorous dose loss and diffusion to the bulk are strongly suppressed in comparison to Ge substrate without nitrogen implantation. Possible physical mechanisms (involving phosphorous-vacancies or phosphorous-nitrogen complexes, and end-of-range interstitials) that explain this result are presented and discussed.