The behavior of H-vacancy defects in material which had been implanted with 60keV H ions, to a dose of 1016/cm2, was investigated by means of slow-positron lifetime and Doppler-broadening techniques. It was found that the positron-trapping defect which was associated with H formed within the H implantation profile. This gave rise to a long positron lifetime which was close to that which was characteristic of a monovacancy. However, the Doppler broadening parameter of this defect was not as large as that of the monovacancy, since positrons annihilated electrons of H within the defect. Upon annealing at up to 400C, defects which were located within 350nm of the surface agglomerated and hydrogenated. However, H-decorated defects within the H implantation profile were unchanged. Hydrogenation stabilized and immobilized the defects in this temperature range. Annealing at 500C led to the agglomeration of H-decorated defects in the vicinity of the peak of the H implantation profile. Annealing at 600C led to H release from these agglomerates. It was found that a high density of H-stabilized defects was present within the implantation profile upon annealing at 400C. This high density permitted the formation of larger vacancy clusters during higher temperature annealing.

Thermal evolution of defects in H-implanted Si studied using monoenergetic positrons M.Fujinami, R.Suzuki, T.Ohdaira, T.Mikado: Physical Review B, 1998, 58[19], 12559-62