Structure, energetics, and dissociation of Si-H bonds at dangling bonds in silicon

We investigate the interaction of hydrogen with dangling bonds in bulk silicon, using first-principles pseudopotential-density-functional calculations. Two geometries are employed: the first is that of a hydrogenated vacancy; the second geometry allows investigation of an isolated dangling bond and minimizes any H-H interactions. The effect of H-H repulsion is quantified. We find that the energy required to remove the hydrogen from the dangling bond and place it in an interstitial position is 2.5 eV. We also investigate the effect of strain in the back bonds on the energy of the Si-H bond. Finally, we propose a low-energy path for the dissociation of the Si-H bond, and discuss the effect of carriers on the dissociation process.