First-Principles Study of Hydrogen Incorporation in Multivacancy in Silicon

We report first-principles total-energy calculations which reveal microscopic structures of multivacancies in Si and their feasibility of hydrogen incorporation. We find that the hexavacancy V 6 and the decavacancy V 10 are stable, and that the multivacancies are capable of containing hydrogen atoms depending on its chemical potential. We also find that an H 2 molecule is trapped in the H-decorated multivacancy. The trapped H 2 molecule as well as the Si–H bonds exhibit peculiar vibration spectra. Recent experimental data is interpreted on the basis of the present theoretical results.