Divacancy and resistivity profiles in n-type Si implanted with 1.15-MeV protons

Defect profiles were determined in proton-implanted low-doped ([P]=1×{}10¹⁴ cm^-3) n-type silicon layers by performing positron-electron pair momentum-distribution measurements with a slow-positron beam, conventional positron lifetime, and e⁺-e^- pair momentum-distribution measurements with a ²²source and spreading resistance measurements. The dominant positron trap induced by 1.15 and 3.0 MeV proton implantations is the silicon divacancy V₂. Compared to the values in bulk, the characteristic positron lifetime and the characteristic low- and high-momentum parameters of the e⁺-e^- pair momentum distribution at the divacancy are τd=300 ps=1.35τb, Sd=1.052Sb, and Wd=0.78Wb, respectively. The divacancy is observed in the negative charge state V₂^-. The divacancy profile is determined in n-type Si implanted with 1.15-MeV (20 {μ}m) protons to a dose 1×{}10¹⁴ cm^-2 and the maximum concentration [V₂^-]=4--8×{}10¹⁵ cm^-3 is observed at depths 16--18 {μ}m. The resistivity increases with increasing divacancy concentration. After annealing at 400 ^∘{}C the spreading resistance measurements reveal a region of shallow hydrogen-related donors at depths 15--21 {μ}m. The positron annihilation results support the idea that the introduction of shallow donors is due to the formation of hydrogen-vacancy complexes during the annealing.