The interaction between hydrogen and a dislocation in silicon was investigated using first-principles calculation. Consideration was given to 30° and 90° partial dislocations with both single and double periodic structures and non-dissociated . screw dislocation starting from the case of one single H to a fully H-filled dislocation line. In the case of a single H atom, H was preferentially located in a bond-centered-like site after a possible breaking of a Si–Si bond. In case of two H atoms, the molecular H2 could be stable but was never the lowest energy configuration. If initially located in a bond-centered site, H2 usually spontaneously dissociates into two H atoms and breaks the Si–Si bond followed by the passivation of resulting dangling bonds by H atoms. When additional H atoms were inserted into partial dislocation cores, they first induce the breaking of the largely strained Si–Si bonds in the dislocation core, then passivate the created dangling bonds. Next the insertion of stable H2 near the dislocation core became favourable. A maximum H density was determined as 6 H atoms per length of Burgers vector and the largest energy gain in energy was obtained for a 90° single periodic partial dislocation. The calculations also suggested that the presence of few hydrogen atoms could have a non-negligible influence upon the dislocation structures, inducing core reconstructions. The mobility of H along the dislocation line was briefly addressed in the case of the 90° single periodic partial dislocation core.

Theoretical Study of Hydrogen Stability and Aggregation in Dislocation Cores in Silicon. M.Matsubara, J.Godet, L.Pizzagalli: Physical Review B, 2010, 82[2], 024107