The use of proton implantation and 2-step annealing, to obtain a high-resistivity buried layer beneath the surface, was investigated by means of transmission electron microscopy. It was found that the implantation produced a heavily damaged region which contained 2 types of extended defect that involved H. These defects were (001) platelets and {111} platelets. During a first annealing stage, gas bubbles and {111} precipitates formed. During a second annealing stage, the {111} precipitates disappeared, while the bubble microstructure remained; plus a buried layer that consisted of bubbles and dislocations between the bubbles. The results showed that the dislocations which pinned the bubbles played an important role in stabilizing the bubbles and in forming a defect insulating layer.

M.Gao, X.F.Duan, J.Li, F.Wang: Journal of Applied Physics, 1996, 80[8], 4767-9