Oxygen-Related Donors Stable at 700–800°C in CZ–Si Crystals

A variety of silicon-oxygen clusters have been induced in CZ–Si crystals by multi-step annealing at temperatures between 450 and 800°C. Five-step annealing (450°C, 100 h+500°C, 40 h+600°C, 20 h+700°C, 20 h+800°C, 20 h) has generated oxygen-related donors at a concentration of more than 1015 cm-3. The silicon-oxygen clusters were investigated using infrared absorption, resistivity, photoluminescence and TEM. In carbon-lean CZ–Si crystals, oxygen-related donors, which are stable at 700–800°C, were found to be related to both oxygen clusters nucleated at dislocation dipoles and to the so-called thermal donors. However, in carbon-rich CZ–Si crystals, oxygen-related donors, which are stable at 700–800°C, were related to oxygen clusters nucleated at carbon atoms, which can gather many oxygen atoms without forming dislocation dipoles.