Effects of pressure and hydrogen on the formation of vacancies and divacancies in crystalline silicon

Abstract

The electron-density functional and pseudopotential methods are used to study the effects of hydrogen and pressure on the formation of vacancies and divacancies in silicon. It is shown that the formation energy of vacancies can be reduced by 1.8–3.5 eV and that of divacancies by 2.0–5.4 eV in the presence of hydrogen. As a result, the spontaneous generation of vacancies and vacancy-containing complexes becomes possible at high concentrations of hydrogen. At the same time, the presence of hydrogen makes silicon less sensitive to pressure and, at high hydrogen concentrations, can completely suppress the tendency toward additional formation of vacancies in the sample exposed to pressure.