Selective adsorption of C60 on Ge/Si nanostructures.

Selective adsorption of C60 on nanoscale Ge areas can be achieved, while neighboring Si(111) areas remain uncovered, if the whole surface is initially terminated by Bi. Fullerene chemisorption is found at Bi vacancies which form due to partial thermal desorption of the Bi surfactant. The growth rate and temperature dependence of the C60 adsorption were measured using scanning tunneling microscopy and are described consistently by a rate equation model. The selectivity of the C60 adsorption can be traced back to an easier vacancy formation in the Bi layer on top of the Ge areas compared to the Si areas. Furthermore, it is also possible to desorb C60 from Ge areas, allowing the use of C60 as a resist on the nanoscale.