C60 layer growth on intact and Tl-modified Si(111)5×2-Au

Applied Surface Science. 2018. Vol. 456. P. 801–807.

Olyanich D. A., Mararov V. V., Utas T. V., Aladyshkin A. Y., Mihalyuk A. N., Zotov A. V., Saranin A. A.

The Si(111)5×2-Au surface comprises a quasi-one-dimensional surface reconstruction consisting of Au stripes mediated by honeycomb Si chains. In the present study, using STM observations we explored adsorption of thallium (Tl) onto Si(111)5×2-Au surface as well as growth of C60 layers on Tl-modified and intact Si(111)5×2-Au surfaces. Analysis of the results was based on the recently proposed KK model of Si(111)5×2-Au surface [Kwon and Kang, PRL 113 (2014) 086101]. It was found that intact Si(111)5×2-Au surface produces a poor template effect on the overgrown C60 layers which have a close-packed-like structure without distinct ordering. In contrast, the C60 layers grown on the Tl-adsorbed Si(111)5×2-Au surface where Tl atoms occupy various adsorption sites on the honeycomb Si chains have a well-ordered quasi-one-dimensional structure consisting of straight C60 chains. Ordering of the C 60 molecules is a result of an intricate interplay between adsorbed C60 molecules with each other and with a substrate surface. Separation between neighboring C60 chains is dictated by the periodicity of the underlying Si(111)5 × 2-Au template, while the C60-C60 spacing within the chains of ∼12 Å that is ∼3.2a0 reflects the peculiarity of the C60-C60 intermolecular interaction on the Tl-adsorbed Si(111)5×2-Au surface. Structural information on (Au, Tl)/Si(111) and C 60 /(Au, Tl)/Si(111) systems gained in the present study can be useful for the prospective works on elucidating the ways to control electronic properties of the Si(111)5×2-Au surface using atomic and molecular adsorbates.

Keywords: scanning tunneling microscopy, fullerenes, Self-assembly