The effect of hydrogen passivation on Si nanocrystals: Surface and spin states

In this paper hybrid density functional theory has been used to study the electronic properties of silicon nanocrystals (SiNCs) having 75, 150 and 300 silicon atoms with and without hydrogen passivation. Wurtzite structure has been found to be more stable than the diamond structure irrespective of the passivation at the sizes considered here. In addition to the HOMO–LUMO gap broadening, the hydrogen passivation was found to affect the orbital distribution of the passivated SiNC. It has been also found that, the stability of the higher spin-state structures, even with hydrogen passivation, are very close to the lowest energy singlet structure and have very small gaps at these size levels.