Hydrogen-related center with tetrahedral symmetry in ion-implanted silicon

The effect of uniaxial stress on a local vibrational Si-H stretching mode observed at 2223 cm^-1 in proton-implanted silicon has been studied by means of infrared-absorption spectroscopy. It is found that the defect responsible for the 2223-cm^-1 line has a tetrahedral point group. Measurements on samples implanted with hydrogen and deuterium reveal that the defect involves more than one hydrogen atom. A detailed analysis based on the valence-force approximation indicates that the line is associated with the hydrogenated vacancy or with monosilane located at the interstitial tetrahedral site. The stress-induced splittings of the line can be analyzed with a single parameter which describes the change in the effective force constant of the Si-H bond when uniaxial stress is introduced parallel to the bond.