DIVACANCY AND RESISTIVITY PROFILES IN N-TYPE SI IMPLANTED WITH 1.15-MEV PROTONS

摘要

Defect profiles were determined in proton-implanted low-doped ([P]=1X10(14) cm(-3)) n-type silicon layers by performing positron-electron pair momentum-distribution measurements with a slow-positran beam, conventional positron lifetime, and e(+)-e(-) pair momentum-distribution measurements with a Na-22-source and spreading resistance measurements. The dominant positron trap induced by 1.15 and 3.0 MeV proton implantations is the silicon divacancy V-2. 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 tau(d)=300 ps=1.35 tau(b), S-d=1.052S(b), and W-d=0.78W(b), respectively. The divacancy is observed in the negative charge state V-2(-). The divacaney profile is determined in n-type Si implanted with 1.15-MeV (20 mu m) protons to a dose 1X10(14) cm(-2) and the maximum concentration [V-2(-)]=4-8X10(15) cm(-3) is observed at depths 16-18 mu m. The resistivity increases with increasing divacancy concentration. After annealing at 400 degrees C the spreading resistance measurements reveal a region of shallow hydrogen-related donors at depths 15-21 mu 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. [References: 40]