Fluorine-Related Defects in BF₂ ⁺-Implanted Si Probed by Monoenergetic Positron Beams

Abstract

Fluorine-related defects in 30-keV BF 2 + -implanted Si were probed using monoenergetic positron beams. From measurements of Doppler broadening profiles of the annihilation radiation as a function of incident positron energy and those of lifetime spectra of positrons, depth profiles of defects and the species of the defects were determined. For an as-implanted specimen, the major species of the defects below the amorphous region was identified to be divacancies. Upon rapid thermal annealing above 700 °C, solid phase epitaxial growth of the amorphous region started, but no shift of the depth profile of defects detected by the positron annihilation technique was observed. During the regrowth of the amorphous region, vacancy-fluorine complexes were introduced. The complexes between vacancy clusters and fluorine atoms were observed even after 1100 °C annealing.