A study was made of [100]-oriented wafers which had been irradiated, with 2.5MeV electrons at 4K, to doses of up to 3 x 1019/cm2. The irradiation-induced defects and their thermally activated reactions were investigated by measuring the diffuse scattering close to Bragg reflections, and changes in the lattice parameter. In the case of Ge, a distribution of the diffuse intensity was observed which indicated the presence of close Frenkel pairs. These pairs were produced at a rate of about 1/cm, and defect concentrations of about 1019/cm3 were obtained with no sign of saturation. A very small change in the lattice parameter also showed that the displacement fields of the vacancies and interstitials cancelled each other almost exactly at larger distances. In the case of Si, a similar production of close Frenkel pairs and the superposed growth of larger defect agglomerates was observed. In agreement with this more complex defect pattern, the annealing was much slower here than in Ge.

S.Bausch, H.Zillgen, P.Ehrhart: Materials Science Forum, 1995, 196-201, 1141-6