Variously-doped, and undoped, samples were irradiated with electrons in order to study the formation of non-equilibrium defects and their annealing behavior. The annealing data, as monitored by means of positron lifetime and Doppler-broadened annihilation techniques, depended markedly upon the doping concentration and the O content. Temperature-dependent positron-lifetime measurements, beginning at 15K, were also made after low-temperature and room-temperature irradiation to various doses and in various annealing states. Shallow positron traps were detected in irradiated material of all conductivity types. However, the concentration of shallow traps depended upon the crystal-growth procedure. Electron-irradiated Czochralski-type samples contained a higher number of shallow traps than did electron-irradiated float-zone material. Due to the differing concentrations of O in these differently grown samples, it was concluded that the O atoms formed part of the traps. One possible candidate was the irradiation-induced A-center.

Defects in electron-irradiated Si studied using positron-lifetime spectroscopy A.Polity, F.Börner, S.Huth, S.Eichler, R.Krause-Rehberg: Physical Review B, 1998, 58[16], 10363-77