IDENTIFICATION OF VACANCY TYPE DEFECTS IN HIGH ENERGY OXYGEN IRRADIATED III-V COMPOUND SEMICONDUCTORS USING POSITRON ANNIHILATION SPECTROSCOPY

摘要

The effect of 140 MeV Oxygen irradiation in S-doped n-type GaP (n ≈ 5 × 10~(17)/cm~3) and InP (n ≈ 5.4 × 10~(18)/cm~3) crystals and post irradiation isochronal annealing from 23-800℃ for GaP and 23 - 600℃ for InP are investigated using positron annihilation measurements. The high average positron lifetime τ_(avg) = 261 ps in GaP indicates the presence of irradiation induced defects. Two distinct annealing stages at 150-250℃ and 450-600℃ are found indicating the recovery of defects in Ga sublattice. In InP, a sharp annealing stage occurs at temperature 100-200℃ indicating the changes in defect configuration followed by a clustering of vacancies over 200-500℃. During 500-600℃ the complete disappearance of positron signal takes place. Both positron lifetime and annihilation line shape measurements are done in InP.