C. Mathieu, J.-J. Gallet, F. Bournel, G. Dufour, F. Rochet
Laboratoire de Chimie Physique Matière et Rayonnement
Université Pierre et Marie Curie, Paris
M. Silly. C. Chauvet, F. Sirotti
Tempo Beamline, Synchrotron-SOLEIL
The modification of surfaces with organic molecules represents a promising approach for the incorporation of new functionalities into semiconductors. The Si(001)–2x1 reconstruction attract much attention as it can be used as a template for the grafting of organic molecules arrays. However most of interesting molecular objects to be grafted directly on a semiconductor surface are multifunctional which in most cases leads to competitive reactions with the surface silicon atoms and to multiple adsorption geometries.
Tetramethylethylenediamine (CH3)2N–(CH2)2–N(CH3)2 reacts with the silicon surface in a dative bonding configuration through the nitrogen lone pair. This state evolves to a dissociative linking between nitrogen and silicon with the cleavage of C–N bonds.
In the figure, we show the real time photoemission spectra of the N1s core level as a function of time during gas exposure. The dative bonding (130.9 eV) gradually moves to a dissociative configuration (133.6 eV) without any change in the total amount of surface nitrogen. We have shown that the phenomenon is triggered by gas phase molecules impinging on the surface.
