Stability of Ta-encapsulating Si clusters on Si(111)-(7 7) surfaces

Tantalum containing Si cluster ions TaSi10–13Hx+ were synthesized in an ion trap and deposited onto Si(111)-(7×7) surfaces with a kinetic energy of 18 eV. Scanning tunnelling microscope observations revealed that the clusters adsorbed on the surface without decomposition, consistent with ab initio calculation results, that predicted the clusters would have stable Si-cage structures with a Ta atom at the centre.