REdox active Molecular layers with Ions for Nanoelectroionics Devices – REMIND

REMIND is focussed on multifunctional ultrathin organic films with mixed electronic and ionic conductivity and on emerging devices as defined in the ITRS roadmap within the resistive memory theme. It develops building blocks that can be used in high added value domains and are upstream for nanoelectronic and nanoelectroionic components. It addresses fundamental issues raised by electrochemistry in solid state nano-devices.
We propose to explore the new concepts which apply when the thickness of organic films in devices is in the 5-20 nanometer range. Indeed below such 5 nm thickness, electronic transport is governed by non-resonant tunnelling whereas above 20 nm, thermally activated hopping between molecules dominates. Since the 5-20 thickness range is much shorter than that in today’s organic electronic devices and since device thickness is of the same order of magnitude compared to scattering, hopping lengths and charge carrier sizes, the electronic transport in REMIND will be truly “nanoscale” and mainly intramolecular. As a consequence transport will be almost activation-less and potentially ultrafast. Since this thickness range is above the non-resonant tunneling limit, the transport will also be truly molecular and much more sensitive to the structural and electronic properties of the molecules in the layer.

By creating multifunctional molecular films 5-20 nm thick and by exploiting, phenomena not available with silicon or organic electronic devices, namely redox events and ultrafast ion motion within ultrathin layers, we thus seek to provide low cost, low energy consumption electronic and opto-electronic functions including giant rectification and nonvolatile memory with possibly widespread applications.

The fabrication process of the organic layers used in REMIND is based on electro-generated radical grafting processes using diazonium salt reduction. In the present proposal it is a key technology that makes possible the direct evaporation of various metals on the grafted organic layer in order to fabricate the top electrode through fully CMOS compatible processes. The use of such robust layers will avoid that of Self Assembled Monolayers (SAM), widely developed by many scientific groups worldwide, but unable to withstand direct evaporation of metals. The project clearly moves away from SAMs. It also moves away from single molecule devices as reliability and reproducibility cannot be obtained with such devices.

The proposed approach is thus based on a molecular electronic platform which tackles the principal limitations of the field (robustness, variability...) and is “manufacturable” in a massively parallel format, and tolerant of operating temperatures of today’s microelectronic.

The proposed efforts represent a major step away from the “classic molecular electronics” operative when the device thickness is below 5 nm toward “realistic molecular electronics” which exploits phenomena not possible with conventional semiconductors.