Slow minority carrier trapping and de-trapping in Czochralski silicon: Influence of thermal donors and the doping density

The trapping characteristics of defects related to thermal donors have been studied with transient photoconductance measurements in Cz monocrystalline silicon wafers. The samples were annealed for various lengths of time to create a range of thermal donor concentrations. The de-trapping time constant was measured using photoconductance decay after the illumination is turned off. In order to obtain an estimate of the de-trapping time constants, the measurements were fitted with exponential terms. We find that the de-trapping time constant is inversely related to the concentration of thermal donors, while trapping is not observed in samples without thermal donors.