One- and two-detector Doppler broadening measurements performed on low (about 1014 to 1015O+/cm2) and high dose (about 1017 to 1018O+/cm2) O-irradiated Si using variable-energy slow positrons were analyzed in terms of S and W parameters. After annealing the low-dose samples at 800C, large VxOy complexes were formed at depths around 400nm. These complexes produce a clear-cut signature when the ratio of S to that of defect-free bulk Si was plotted. Similar behavior was found for samples irradiated with 2 and 4 x 1017O+/cm2 and annealed at 1000C. After irradiation with 1.7 x 1018O+/cm2 and anneal at 1350C a 170nm-thick almost-bulk-quality Si surface layer was formed on top of a 430nm-thick buried oxide layer. This method of preparation was called separation by implantation of O. S–W measurements showed that the surface layer contained electrically inactive VxOy complexes which were not seen by using electron microscopy. A method was developed for decomposing the Doppler broadening line-shape into contributions arising from the bulk, surface and defect.

Buried Oxide and Defects in Oxygen Implanted Si Monitored by Positron Annihilation. A.C.Kruseman, A.van Veen, H.Schut, P.E.Mijnarends, M.Fujinami: Journal of Applied Physics, 2001, 90[3], 1179-87