Ab initio configuration-interaction theory is used to study Si-H bonds in the a-Si:H and O-doped a-Si:H:O systems. The a-Si:H is modeled by a finite Bethe lattice containing 13 Si atoms and 28 H atoms with a local configuration of 3(Si)-SiH. By the incorporation of three O atoms in the cluster, the a-Si:H:O system is modeled to have a local configuration of 3(O)-SiH. The H dissociation energy is calculated to be 3.55 eV in 3(Si)-SiH and 4.11 eV in 3(O)-SiH. A 1.5% decrease in the Si-H bond length and 5.1% increase in the Si-H stretching frequency are found with the incorporation of three O atoms. Incorporation of O atoms increases the electron loss from the Si atom of the SiH group strengthening the SiH bond.

• Received 4 November 1991

DOI:https://doi.org/10.1103/PhysRevB.45.13978