Tuning the thickness of electrochemically grafted layers in large area molecular junctions

T Fluteau (1) , C. Bessis (1) , C. Barraud (2) , M. L. Della Rocca (1) , P. Martin (3) , J.-C L Lacroix (3) , P. Lafarge (1)

1 MPQ (UMR_7162) - Laboratoire Matériaux et Phénomènes Quantiques
2 UMS 831 - Services communs OMP
3 ITODYS (UMR_7086) - Interfaces, Traitements, Organisation et Dynamique des Systèmes

We have investigated the thickness, the morphology and the transport properties of oligo(1-(2-bisthienyl)benzene) (BTB) thin films grafted on evaporated Au electrodes thanks to a diazonium-based electro-reduction process. Atomic force microscope (AFM) measurements reveal that the thickness is accurately controlled by the number of electrochemical cycles in the 2-27 nm range. The thickness displays a linear dependence with the number of cycles followed by a saturation. Ultrathin (2 nm) and thin (27 nm) large area molecular junctions have then been fabricated. The current-voltage characteristics is fully consistent with a tunneling barrier model whereas for thicker molecular films a rectifying behavior is observed.

Domains: Physics [physics]; Condensed Matter [cond-mat]; Materials Science [cond-mat.mtrl-sci]; Engineering Sciences [physics]; Micro and nanotechnologies/Microelectronics

T Fluteau, C. Bessis, C. Barraud, M. L. Della Rocca, P. Martin, et al.. Tuning the thickness of electrochemically grafted layers in large area molecular junctions. Journal of Applied Physics, 2014, 116 (11), pp.114509. ⟨10.1063/1.4896106⟩. ⟨hal-01822392⟩