Fast-forming boron-oxygen-related recombination center in crystalline silicon

The mechanism of a fast carrier lifetime degradation effect proceeding within seconds in boron-doped Czochralski silicon is investigated. The decrease in the carrier lifetime is attributed to the formation of a deep boron-oxygen-related recombination center with a strongly asymmetric electron-to-hole capture cross section ratio of 100. The center is activated in a two-step process. In a first step, the electron quasi-Fermi level has to be shifted above an energy level at EV+0.635eV before, in the second step, the actual activation occurs via a thermally activated process with an energy barrier of 0.23eV. A defect model is proposed to explain the observed activation behavior.