Lattice disorder studies in low-temperature nitrogen-implanted silicon

Abstract

The amount of lattice disorder and its depth distribution in silicon crystals implanted to a total dose of 10¹⁴ nitrogen ions/cm² at 80 keV have been investigated as a function of implantation temperature (25-300°K) and of dose rate (5-500 na/cm²), using the helium-backscattering technique. Evidence has been found for a strong reverse-annealing stage at the lower temperatures (< 80°K), indicating the existence of mobile defects in silicon down to 25°K. The depth distribution and dose-rate dependcnce of damage resulting from this reverse annealing stage implies the existence of an ionization-induced mobile defect, probably the negative vacancy.