Self-assembly of C60 layers at Tl/NiSi2 atomic sandwich on Si(111)

Abstract Self-assembled growth of C 60 monomolecular layers at the atomic sandwich consisting of Tl-covered single-layer NiSi 2 on Si(111) has been studied as a function of the density of the Tl atomic layer. It has been found that C 60 fullerenes form hexagonal close-packed arrays. Within a C 60 layer, fullerenes can form together with Tl atoms three distinct configurations which are reflected by difference of the C 60 brightness, labelled as dim, normal and bright, in the scanning tunneling microscopy images. It has been elucidated that the bright fullerenes reside atop a completed Tl monolayer, in the case of the normal fullerenes one Tl atom directly beneath the given fullerene is missing, and under the dim fullerenes no Tl atoms are left. Using Tl deposition, it is possible to change the relative fractions of the dim, normal and bright fullerenes, in particular to fabricate the homogeneous C 60 layers consisting exclusively of the fullerenes of a single type, normal or bright, depending on the desire.