Energetics of bond-centered hydrogen in strained Si-Si bonds

The energetics of hydrogen incorporation into strained Si-Si bonds are examined using first-principles density-functional-pseudopotential calculations. It is found that an increase in the bond length of the initial Si-Si bond leads to a lower formation energy for the Si-H-Si configuration. A simple linear relationship, describing the change in formation energy as a function of the Si-Si bond length, is presented, which applies to bond-stretching as well as bond-bending distortions. The results are discussed in the context of hydrogen interaction with grain boundaries in polycrystalline silicon.