Abstract EN:

My project dealt with achievement and study of isolated molecules on boron silicon surface (OD system), molecular self-alignment on samarium/silicon interface (1D system) and 2 dimensionnel molecular self-assembly on Si(111)-7x7 and Si(111)-B surfaces (2D system). In order to circumvent the problem of traditional silicon surface reactivity with TT-conjugated molecules, we use the Si(111 )-B surface. This surface has the unique particularity to exhibit depopulated dangling bonds due to the presence 01 boron atoms under the top silicon layer. Consequently, TT-conjugated organic molecules can interact weakly with the pz depopulated dangling orbitals of the surface. To achieve self-alignment of organic molecules, we used an innovative concept based on the template effect of the pre-structured semi- conductive SmSi(111) interface. This substrate was selected because Sm deposition in the submonolayer range leads to a 8x2- reconstruction, which is a well-defined one-dimensional semi-metallic structure. Adsorption of aromatic molecules [1,4- di-(9- ethynyltriptycenyl)-benzene] on SmSi(111)-8x2leads to a good self-alignment of molecules along the [1-10] direction and the molecules are parallel to the atomic rows of the 1 D SmSi(111)- 8x2 structure. To create 2 dimensionnel molecular self-assemblies on silicon surface at room temperature,we proposed two new strategies: The first uses the zwitterionic molecules [4-methoXy-4'-(3-sulfonatopropyl)- stilbazolium ] and Si(111)- 7x7 surface. The second technique is based on the choice of the molecule/substrate system. We chose SiB surface in order to reduce molecules/substrate interaction and a highly polar molecule (4-aminobenzonitrile) to promote molecule/molecule interactions.