Recently a composite group of researchers from the University of Toulouse including Dr J. Grisolia, Dr B. Viallet and Dr L. Ressier (LPCNO/CNRS), C. Amiens, S. Baster from the Laboratoire de Chimie de Coordination (LCC – CNRS), A.S. Cordan and Y. Leroy from the the Institut d'Electronique du Solide et des Systèmes (InESS-CNRS), Dr Caterina Soldano (CEMES/CNRS) and J. Bruggerat the Ecole Polytechnique Fédérale Lausanne (EPFL), report a fast and low-cost process to fabricate and electrically address parallel micrometric stripes of closely-packed 20 nm gold nanoparticles on SiO2 substrates without any patterning of the substrate.
Metallic and semiconductor nanoparticles are increasingly being used in the fabrication of advanced microelectronics and micro-systems. Nanoparticles can be integrated in flash memories as a floating gate, form a sensitive layer in humidity, vapour or gas sensors, act as markers in biochips and operate as piezo-resistive structures in strain gauges and other devices.
For all of those applications, nanoparticles can be elaborated during fabrication of the device or deposited from a suspension of chemically synthesized nanoparticles. In the latter case, maintaining the properties of the nanoparticles and their stabilizing ligands during device processing can be a crucial issue. As a result, a method that avoids resist-based processes, which could contaminate the substrate and/or the nanoparticles, is required.
The research team at University of Toulouse First devised an assembly method based on nanoparticle deposition by a convective/capillary method that allows the formation of compact and well-organised arrays of nanoparticles. Then, stencil lithography permits the team to electrically address the nanoparticle assembly without substrate patterning and with no contamination/degradation of either the substrate or the nanoparticles.
The group applied its approach to gold nanoparticle µ-stripes. Under certain conditions, I(V) and I(t) measurements revealed current fluctuations, an unusual relative amplitude of up to 99% random telegraph signal (RTS) noise was observed. The investigation of this RTS-like noise can offer some unique opportunities to understand the low frequency noise in such structures, in particular, the role of ligands, nanoparticle organization and size dispersion of nanoparticles. The researchers are now optimizing their technique and plan to apply it to biological objects and to use it to elaborate functional nano-devices.
Further information in: J Grisolia et al 2009 Nanotechnology 20 355303; and in ad corrigendum: J Grisolia et al 2009 Nanotechnology 20 489801