Perturbed angular correlation techniques were used to study the creation and development of He-induced cavities. In order to investigate the interaction of In atoms with cavities, an isotope separator was used to implant overlapping profiles of 10keV He and 160keV radioactive 111In into undoped float-zone samples. They were prepared by using various He doses (6 x 1015 to 6 x 1016/cm2). The samples were measured straight after implantation, and after annealing (500 to 1100C, 600s). It was found that, after higher He doses (2 x 1016 and 6 x 1016/cm2), a large fraction of the 111In probe atoms was subject to an electric field gradient which corresponded to a quadrupole interaction frequency of 411MHz. The corresponding defect configuration formed most effectively after the He implantation of annealed 111In-doped material. This observation, and the affinity of In for vacancies, led to the conclusion that the In atoms acted as nucleation centres for vacancy clusters and were situated on the inner walls of the cavities.

Cavities in Silicon Investigated with the PAC-Probe 111In J.Bartels, C.Noll, R.Vianden: Hyperfine Interactions, 1999, 120-121[1-4], 353-8