One- and two-detector Doppler broadening measurements performed on low (about 1014 to 1015O+/cm2) and high dose (about 1017 to 1018 O+/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 400 nm. 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 1017 O+/cm2 and annealed at 1000C. After irradiation with 1.7 x 1018O+/cm2 and annealing 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 termed separation by implantation of O. S–W measurements showed that the surface layer contained electrically inactive VxOy complexes not seen by electron microscopy. A method was presented to decompose the Doppler broadening line shape into contributions of 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