Core–shell structures of silicon nanoparticles and nanowires with free and hydrogenated surface

The molecular dynamics has been used to simulate the structures of Si nanoparticles (NPs) and nanowires (NWs) with free and hydrogenated surface. Both NPs and NWs can be regarded as core–shell structures, for which the bond length in the core expands but that in the shell contracts. However, the cohesive energy in the core keeps the bulk value, while that in the shell decreases. The formation of Si–H bonds causes tensile strain in the surface, which can passivate the surface. The present study confirms the importance of surface in dominating the properties of NPs and NWs.