Recombination in Si after thermal treatment and γ-irradiation

The effect of processes occurring in silicon under heat treatment (HT) on its recombination parameters under following γ-radiation was investigated. Heat treatment was conducted at 450 deg C. Samples of n-silicon alloyed with gadolinium from melt and diffusion p-n transitions were investigated. Lifetime of minority charge carriers (τ) was measured. It is shown that for samples with gadolinium impurity lifetime grows at increase of heat treatment duration, and it is as large as higher gadolinium content is, i. e. decrease of efficiency of getters is followed by decrease of concentration of the recombination centers. Increase of τ is not observed in p-n transitions, but the value of lifetime degradation constant increases. It is associated with defects introduced under production of samples or with change of recombination activity of radiation-induced defects as a result of change of Fermi level position under heat treatment