Field Ion-Scanning Tunneling Microscopy Study of C₆₀ on the Si(100) Surface

Abstract

Field ion-scanning tunneling microscopy was employed to study the monolayer and multilayer adsorption behaviors of the C60 fullerene on the Si(100)2×1 surface. The C60 molecules reside stably in the trough at room temperature without rotation, encompassing the 8 neighbouring dimer-forming surface Si atoms with the nearest neighbour distance of 12 Å. For the first and second layers, only local ordering of square and quasi-hexagonal patterns was observed. The orderly Stranski-Krastanov mode island formation with the hexagonal packing was observed above the third layer with its lattice constant of 10.4 Å.

Adsorption of N@C60 on Si(100)

“…Many studies [6][7][8][9][10][11][12] have been carried out experimentally which show that the C 60 molecule adsorbs in the dimer trench at room temperature, and is only observed above the dimer row when the system is heated. A study of the larger endohedral La@C 82 molecules suggested that the adsorption of an endohedral molecule is similar to that of a fullerene without the presence of an endohedral atom [13].…”

Adsorption of C82 on Si(100)

“…The behaviour of the fullerene cages upon silicon is therefore intrinsically very important to the feasibility of such systems and has been studied both computationally [1][2][3][4] and experimentally [5][6][7][8][9][10][11]. Experimental studies have also examined the manipulation of the cage upon the surface by a suitable device, most often a scanning tunnelling microscope (STM) tip [12,13].…”

“…Experimental studies mainly show that the C 60 molecule adsorbs in the dimer trench bonded to four dimers at room temperature [7,5,13] and only moves to sit on the dimer rows when heated. A study of C 84 and the endohedral fullerene La@C 82 [14] found that these larger molecules would also adsorb above the dimer row at room temperature and this was attributed to the larger radius of curvature.…”

The bonding sites and structure of C60 on the Si() surface

“…Some workers in this field have obtained results which imply that the molecule is physisorbed [2][3][4] whilst the results of others show chemisorption [5][6][7][8][9][10]. A few ab-initio theoretical calculations have been carried out [11][12][13] but these have all used pre-assumed structures, created by placing fullerenes above the substrate and ignoring any structural rearrangement caused by the interaction between the fullerene and the silicon surface.…”