On the Influence of Molecular Linker on Charge Transfer Rate in Hybrid Molecular (Ferrocene)/Silicon Field Effect Memories

In this work, a physical and electrical investigation of hybrid molecular/Si memory capacitor structures is proposed, where redox active molecules act as storage medium. Ferrocene molecules were grafted on (100) Silicon either directly or with a chemical linker, in order to investigate the electron transfer properties of the molecule/silicon system. The chemical structures of the molecular layers were analyzed with X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry on macroelectrodes and impedance spectroscopy on capacitor structures were performed in order to characterize the charge transfer between the redox molecules and the Silicon, showing the effect of the organic linker. Finally, to explain our results, an original electrical model of ferrocene/Si field effect devices is proposed. The model allows to give a theoretical confirmation of the influence of the linker over the redox energy. DFT calculations provide further explanations of the effect of the linker on redox energy. The results obtained in this paper show the strong impact of the engineering of the redox molecules on the electron transfer properties.