The production and structure of the P-P3anti-site defect in electron-irradiated n-type GaP

Samples of n-type GaP doped with either (a) sulphur or (b) silicon to concentrations of about 10 18 atoms/cm 3 have been compared using EPR and IR measurements following a series of small doses of 2 MeV electron irradiation at room temperature. The EPR spectrum due to the (P-P 3 ) antisite defect is produced up to a similar strength in both materials. The measurements suggest that it is unlikely that the defect involves an impurity. The authors speculate that the (P-P 3 ) centre may be a gallium vacancy distorted to give (V p -P Ga ) or a trigonal (V P -P Ga -Ga i ) complex produced by a knock-on process.