Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 32: Semiconductor Substrates

O 32.6: Talk

Tuesday, March 27, 2007, 17:00–17:15, H39

Individual molecules of hexaphenyl on Si(100)-2x1 — •Marion Cranney, Marta Martin, Andrew Mayne, Damien Riedel, and Gérald Dujardin — Laboratoire de PhotoPhysique Moléculaire, Orsay, France

Hexaphenyl molecules are very attractive for applications in molecular opto-electronics since they have quite interesting electrical and optical properties.

We have worked with a LT-STM at 5 K in order to study the structural properties of individual hexaphenyl molecules on Si(100)-(2x1). We observed that this molecule is weakly chemisorbed on Si(100) when deposited at 5 K. We analysed carefully STM pictures of each conformation in order to understand how the molecule of hexaphenyl interact with silicon dimers.

Moreover we have investigated the electronic and dynamical properties of these molecules with the LT-STM by exciting each phenyl ring of different conformations of the molecule with voltage pulses. The molecule change its conformation reversibly without diffusing across the surface. The location of the pulses on the molecule determines the molecular dynamics. This is due to different interactions of each phenyl with the silicon atoms, an effect that is shown by measurements of scanning tunneling spectroscopy.