Can Hydrogen be Incorporated inside Silicon Nanocrystals?

Hydrogen is omnipresent during the synthesis and processing of silicon nanocrystals (Si NCs). It is generally assumed that the incorporation of hydrogen leads to the passivation of Si dangling bonds at the NC surface. However, it is also speculated that hydrogen may be incorporated inside Si NCs. In this work the formation energy and probability of hydrogen in its three configurations, i.e., hydrogen molecules, bond-centered atomic hydrogen, and antibonding atomic hydrogen, are calculated to rigorously evaluate the incorporation of hydrogen inside Si NCs. We find that hydrogen cannot be incorporated inside Si NCs with a diameter of a few nanometers at temperatures up to 1500 K.