Study of point-defect aggregates in nearly perfect silicion single crystals using a high-resolution diffuse X-ray scattering technique

High-resolution diffuse X-ray scattering (DXS) measurements have been made on dislocation-free silicon single crystals of the following types: (1) as-grown specimen with no heat treatment (labelled as NHT); (2) specimen heated at 1273 K under oxygen for 10 h [labelled as HT(1)] and (3) specimen heated at 1273 K under oxygen for 50 h [labelled as HT(2)]. Reciprocal space around the 111 reciprocal-lattice point in (1,-1,1) geometry has been explored using a Cu Kα exploring beam. From the distribution of DXS intensity it was found that for sample NHT, the observed DXS is predominantly due to aggregates of vacancies. Heating the specimen under oxygen produces defect aggregates of interstitial type. Infrared absorption measurements showed that the area under the 9 μm absorption band decreases, suggesting that oxygen ions aggregate into clusters of interstitial type. Transmission X-ray topographs also support these results.