Observation and theory of the $V{-\mathrm{O}-\mathrm{H}}_2$ complex in silicon

The interaction of hydrogen with radiation-induced defects (RD’s) in Czochralski-grown silicon crystals has been studied by infrared-absorption spectroscopy and ab initio modeling. Hydrogen and/or deuterium was introduced into the crystals by indiffusion from ${\mathrm{H}}_2$ $\left({\mathrm{D}}_2\right)$ gas at $1200–1300°\mathrm{C}.$ The samples were subsequently irradiated with fast electrons $(E=2\mathrm{}-4\hspace{0.5em}\mathrm{MeV})$ and annealed in the temperature range of $100–600°\mathrm{C}.$ The centers produced by the irradiation were the same in both the untreated and treated cases, namely the A-center, ${\mathrm{C}}_i-{\mathrm{O}}_i$ complex, and divacancy. A heat treatment of the H-treated samples resulted in the enhanced loss of these centers and the formation of centers containing hydrogen. The disappearance of the A centers in the temperature range of $100–150°\mathrm{C}$ is correlated with the appearance of three local vibrational modes (LVM’s) at 943.5, 2126.4, and $2151.5\hspace{0.5em}{\mathrm{cm}}^{-1}.$ The isotopic shifts of these lines were obtained from measurements on the samples doped with hydrogen and deuterium. The lines are identified as related to stretching vibrational modes of a complex that consists of one oxygen and two hydrogen atoms sharing a vacancy site $(V-\mathrm{O}-{\mathrm{H}}_2$ complex). Ab initio calculations are used to explore the structures and properties of this defect. The origin of other LVM bands, which were observed upon annealing, is discussed.