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

Defect profiles were determined in proton-implanted low-doped ([P]=1X1 0(14) cm(-3)) n-type silicon layers by performing positron-electron pa ir momentum-distribution measurements with a slow-positran beam, conve ntional positron lifetime, and e(+)-e(-) pair momentum-distribution me asurements with a Na-22-source and spreading resistance measurements. The dominant positron trap induced by 1.15 and 3.0 MeV proton implanta tions is the silicon divacancy V-2. Compared to the values in bulk, th e characteristic positron lifetime and the characteristic low- and hig h-momentum parameters of the e(+)-e(-) pair momentum distribution at t he divacancy are tau(d)=300 ps=1.35 tau(b), S-d=1.052S(b), and W-d=0.7 8W(b), respectively. The divacancy is observed in the negative charge state V-2(-). The divacaney profile is determined in n-type Si implant ed with 1.15-MeV (20 mu m) protons to a dose 1X10(14) cm(-2) and the m aximum concentration [V-2(-)]=4-8X10(15) cm(-3) is observed at depths 16-18 mu m. The resistivity increases with increasing divacancy concen tration. After annealing at 400 degrees C the spreading resistance mea surements reveal a region of shallow hydrogen-related donors at depths 15-21 mu m. The positron annihilation results support the idea that t he introduction of shallow donors is due to the formation of hydrogen- vacancy complexes during the annealing.