Defects created by the decay of radioactive sodium, potassium and magnesium isotopes in n-type Si were studied by capacitance spectroscopy. In particular, attention was paid to the creation of defects due to the large recoil energies involved in the radioactive decay. No evidence was found for an enhanced defect generation with concentrations exceeding those of the implanted mother isotopes. In the present samples, only defects were formed which contained mother or daughter isotopes and vacancies. The decay of 24Na isotopes results in two Mg-related defect levels. After implantation of radioactive 42K one K-related acceptor at Ec-0.269eV was observed. The decay to the stable isotope 42Ca generates the A-center in concentrations comparable to the K-related center. In the decay series of 28Mg via 28Al to 28Si a new level was detected which was thermally unstable at room temperature and converts to the A-center.

Defect Generation by Radioactive Decay of Light Elements in n-type Silicon. J.Bollmann, M.Thieme, J.Weber, Isolde: Physica B, 2006, 376-377, 97-100