Theoretical studies on the core structure of the 450 °C oxygen thermal donors in silicon

Results of molecular- and cyclic-cluster calculations using semiempirical Hamiltonians on a wide range of small oxygen complexes in crystalline silicon are reported. It is shown that a core involving (at most) two oxygens and a self-interstitial can explain the observed behavior of the thermal-double-donor complexes arising in silicon after heat treatment around 450 \ifmmode^\circ\else\textdegree\fi{}C, while all other oxygen complexes proposed so far can be excluded as the core of these centers.