Atomic oxygen in silicon: The formation of the Si—O—Si bond

We study the equilibrium atomic configuration of atomic oxygen in silicon. We calculate the total energy of a cluster of silicon atoms before and after the incorporation of atomic oxygen. The energy is calculated for various atomic configurations to obtain the stable one. The equilibrium atomic distribution involves the separation of the silicon atoms forming a covalent bond to accommodate the oxygen atom. Analysis of the charge distribution reveals the break of the covalent silicon–silicon bond which is replaced by a Si—O—Si puckered bond. A careful analysis of the energy spectrum as well as of the charge-density matrix in the equilibrium configuration indicates the similarity between the new Si—O—Si bond formed and the basic chemical unit of ${\mathrm{SiO}}_2$. Analysis of the rotational and vibrational modes around the defect is in good agreement with infrared-absorption measurements.