A simple technique was presented for the evaluation of defect profiles in ultra-thin Si films on buried SiO2 that was formed by implanting O. Thinning via sacrificial oxidation, and epitaxial film growth via ultra-high vacuum chemical vapor deposition, was used. By measuring the defect density of the epitaxial film, with respect to the thickness before epitaxial growth, the profile of the initial defect density could be deduced. This method was used to study Si-on-insulator structures which had been prepared by means of low-dose (about 4 x 1017/cm2) O implantation and high-temperature internal oxidation. It was found that the defect density at the film surface was 250/cm2. The defect density increased as the buried interface was approached. The defect density at 20nm from the buried interface was as high as 6 x 105/cm2.

A.Ogura, T.Tatsumi, T.Hamajima, H.Kikuchi: Applied Physics Letters, 1996, 69[10], 1367-9