Heat‐Treatment Studies of Oxygen‐Defect‐Impurity Interactions in Silicon

It is shown by electrical property measurements that extended annealing at 450°C introduced ≥ 10 16 cm −3 oxygen‐related donors in Czochralski (Cz)‐grown single crystal (SX) silicon containing ≥10 18 cm −3 interstitial oxygen. The maximum donor concentration attained was ( i ) less if the Si contained carbon, ( ii ) unchanged by n‐type dopants, and ( iii ) increased by p‐type dopants. Short‐term annealing at ≥550°C removed most of the donors in Si not containing aluminum. Most of the donors formed at 450°C in polycrystalline (PX) Cz or cast Si are not removed at 650°C. Annealing at ≥550°C can introduce a different type of donor in Cz SX or PX Si that is stable to ≥900°C. No donor formation was observed in low oxygen content float zone (FZ) SX or PX Si in similar annealings. Aluminum‐doped Cz Si formed donors at ≥650°C, which were stable at 1300°C. If an unknown impurity (presumably lithium) is present in Si, it can be activated as a donor by heat‐treatment at ≥550°C and form a stable donor if associated with lattice defects.