First-principles studies on the adsorptive properties of hydrogenated Si cluster

The adsorption of Si, O and Al adatoms on the most stable hydrogenated Si cluster (Si₆H₁₂) has been explored by using first principles. A special attention is paid to the comparisons of the similarity in adsorptions between the hydrogenated Si cluster and H-terminated Si surface: substitutional adsorption configuration is found for Si atom on Si₆H₁₂ cluster, similar to that on H-terminated Si surface; Si-O-Si adsorption configuration is found for O atom on Si₆H₁₂ cluster, similar to the case on H-terminated Si surface; nonadsorption of Al atom on Si₆H₁₂ cluster is found, similar to the very weak adsorption of Al atom on H-terminated Si surface. This similarity in adsorption between hydrogenated Si₆H₁₂ cluster and hydrogenated Si surface would be attributed to the fact: in hydrogenated Si₆H₁₂ cluster, H atoms have terminated the dangling bonds, and the Si atoms favor the bulk-like sp³ bonding even in this small cluster.