Regensburg 2010 – scientific programme
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O: Fachverband Oberflächenphysik
O 13: Semiconductor substrates: Adsorption
O 13.9: Talk
Monday, March 22, 2010, 17:00–17:15, H34
Potential energy diagram for the selective adsorption of C60 on Bi terminated Si and Ge surfaces — •Vasily Cherepanov1, Stefan Korte1, Sergey Filimonov2, and Bert Voigtländer1 — 1Institute of Bio and Nanosystems (IBN-3), Forschungszentrum Jülich, 52425 Jülich, Germany, and JARA-Fundamentals of Future Information Technology — 2Department of Physics, Tomsk State University, Tomsk 634050, Russia
Si/Ge nanostructures can be grown using a surfactant like Bi in order to suppress Si-Ge intermixing. Choosing appropriate growth conditions one can achieve a chemical selectivity for C60 adsorption and C60 adsorbs only onto the Ge area of the surface. A passivation of dangling bonds on Si and Ge surfaces by Bi atoms results in an adsorption of C60 molecules on top of Bi layer in a physisorbed state. At elevated temperatures the deposited C60 molecules desorb from the physisorbed state back to the gas phase or transfer to a chemisorbed state by substituting Bi and bonding directly to the substrate. The C60 molecules in physisorbed and chemisorbed state can be easily distinguished in Scanning Tunneling Microscopy images. Measurements of the temperature and rate dependences of the density of C60 molecules in physisorbed/chemisorbed state allow to plot the potential energy diagram for adsorption of C60 on Bi terminated Si and Ge surfaces. The knowledge of the adsorption diagrams for Si and Ge is essential to choose the proper growth condition for selective adsorption and thereby to achieve a desired functionality of the surface.