Régis Barattin

From Atomistic to Device Level Investigation of Hybrid Redox Molecular/Silicon Field-Effect Memory Devices

In this paper, an extensive investigation of hybrid molecular/Si field-effect memories is presented, where redox ferrocene (Fc) molecules play the role of the memory charge storage nodes. Engineering of the organic linkers between Fc and Si is achieved by grafting Fc with different linker lengths. The study shows a clear correlation between results from atomistic computational density functional theory, electrochemical measurements (cyclic voltammetry) and electrical data obtained by a detailed study on capacitors and pseudo-MOS devices. Physical-chemical analyses (atomic force microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy), corroborate the quality of molecular layers on devices.

Bistable molecules development and Si surface grafting: two chemical tools used for the fabrication of hybrid molecule/Si CMOS component

For the past ten years, there has been considerable interest dedicated to the miniaturisation of CMOS devices. The research axes followed to obtain scalable devices are numerous as the possibilities offered by both technological (top-down) and new (bottom-up) approaches are studied. Concerning the latter approach molecular electronics is a growing field of interest. Notably, the fabrication of hybrid molecule/Si structures paves the way for development of devices with electrical performances that can be tuned thanks to the molecular properties initially targeted. Here we present the recent results obtained in the two approaches we follow in order to develop new hybrid molecule/Si memory elements. The first axis focuses on the development of specific molecules that could allow a fine tuning of the memory retention characteristic. The second axis deals with the integration of redox molecules inside capacitive cells and the study of their electrical properties. The capacitance of such components clearly shows that an effect of charge transfer is observed only when redox active molecules (porphyrins) are grafted on Si.

NEMS gas sensors for breakthrough GC multigas analysis systems

This paper presents NEMS gas sensors implemented in a breakthrough multigas analysis system. The NEMS mass sensors are collectively fabricated, functionalized and packaged at wafer level. NEMS array resonators exhibit good frequency stability (Allan deviation <;5.10-7 in air). After implementation in the multigas analysis system, the capability to analyze complex gas mixtures for Industrial and Indoor Air Quality monitoring has been demonstrated, with typical Limit of Detection in ppm down to ppb level.

Study of Ferrocene/Silicon hybrid memories: Influence of the chemical linkers and device thermal stability

In this paper we propose an experimental and theoretical analysis of hybrid Ferrocene/Si memory structures. Two main aspects are studied: the influence of the chemical linker length on Ferrocene/Silicon electron transfer rate, and the thermal stability of the hybrid devices. X-Ray Photoelectron Spectroscopy was used to analyse the chemical structure of the molecular layers. Cyclic Voltammetry and impedance spectroscopy were employed to study the charge transfer dependence on the molecular linker. Impedance tests allowed us to evaluate the thermal stability of the molecular memories. The devices were submitted to different annealing temperatures and annealing times. The degradation of the molecular layer and the parasitic oxidation of the device active areas allowed us to explain results. Finally the main molecular parameters were computed through Density Functional Theory (DFT) calculations.

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.