We have developed a simple and reliable method for the fabrication of sub-10 nm wide nanogaps. The self-formed nanogap is based on the stoichiometric solid-state reaction between metal and silicon atoms during the silicidation process. The nanogap width is determined by the metal layer thickness. Our proposed method can produce symmetric and asymmetric electrode nanogaps, as well as multiple nanogaps within one unique process step, for potential application to biological/chemical sensors and nanoelectronics, such as resistive switches, storage devices, and vacuum channel transistors. This method provides high throughput and it is suitable for large-scale production.

We report on a simple process for the chemisorption of poly(thiophene)-based block copolymers onto ITO substrates. Two poly(thiophene) block copolymers functionalized by acrylates on the second block are prepared by the Grignard Metathesis (GRIM) process. The first block is composed of poly(3-hexylthiophene) (P3HT) and the second block is either a polythiophene bearing an acrylate group on each monomer unit (PAcET), or a polythiophene bearing both acrylate and poly(ethylene glycol) side chains (P(AcET-co-PEGET)). After characterizing their macromolecular parameters and optical properties, we investigate their ability to self-assemble into micelles in DMF solutions. This solvent is required for the electrografting procedure that is used for strongly anchoring the polymer to ITO. These micelles are expected to be formed by a P3HT core and a PAcET or P(AcET-co-PEGET) shell. When PEG side chains are present in the second block, the copolymer nicely self-assembles into micelles decorated by acrylates. Cathodic polarization of ITO induces chemisorption and polymerization of acrylate groups, leading to an adherent organized film of poly(thiophene)-based micelles. The optical absorption spectra show that the electrografted polymer chains have a degree of pi-electron conjugation similar to that of crystalline P3HT films. In the absence of the PEG chains, the copolymer does not organize into micelles, due to the low stabilizing ability of the second block in DMF.

A simple protocol for the fabrication of three-dimensional (3D) photonic crystals in silicon is presented. Surface structuring by nanosphere lithography is merged with a novel silicon etching method to fabricate ordered 3D architectures. The SPRIE method, sequential passivation reactive ion etching, is a one-step processing protocol relying on sequential passivation and reactive ion etching reactions using C4F8 and SF6 plasma chemistries. The diffusion of fresh reactants and etch product species inside the etched channels is found to play an important role affecting the structural uniformity of the designed structures and the etch rate drift is corrected by adjusting the reaction times. High quality photonic crystals are thus obtained by adding the third dimension to the two-dimensional (2D) colloidal crystal assemblies through SPRIE. Careful adjustments of both mask design and lateral etch extent balance allow the implementation of even more complex functionalities including photonic crystal slabs and precise defect engineering. 3D photonic crystal lattices exhibiting optical stop-bands in the infrared spectral region are demonstrated, proving the potential of SPRIE for fast, simple, and large-scale fabrication of photonic structures.

We developed a simple and reliable method for the fabrication of sub-10-nm wide nanogaps. The self-formed nanogap is based on the stoichiometric solid-state reaction between metal and Si atoms during silicidation. The nanogap width is determined by the metal layer thickness. Our proposed method provides nanogaps with either symmetric or asymmetric electrodes, as well as multiple nanogaps within one unique process step. Therefore, this method allows for high throughput and large-scale production.

We developed a simple and reliable method for the fabrication of sub-10-nm wide nanogaps. The self-formed nanogap is based on the stoichiometric solid-state reaction between metal and Si atoms during silicidation process. The nanogap width is deter- mined by the metal layer thickness. Our proposed method produces nanogaps either symmetric or asymmetric electrodes, as well as, multiple nanogaps within one unique process step for application to complex circuits. Therefore, this method provides high throughput and it is suitable for large-scale production. To demonstrate the feasibil- ity of the proposed fabrication method, nanogap resistive switches have been built and characterized. They exhibit a pronounced hysteresis with up to 103 on/off conductance ratios in air. Our results indicate that the voltages for initially electroforming the de- vice to the switch state are determinated by the nanogap sizes. However, the set and reset voltages of the device do not strongly dependent on the nanogap widths. These phenomena could be helpful to understand how the resistive switching is established.

The preparation and physical characterization of diverse porphyrin‐derived double‐walled carbon nanotubes (DWCNTs) conjugates are described. A porphyrin molecule is covalently linked and physically adsorbed to COOH‐derived DWCNTs. The photophysical properties of all porphyrin‐CNTs derivatives are studied in solution and in polymeric matrices. Definitive experimental evidence for photoinduced electron and/or energy transfer processes involving the porphyrin chromophores and the CNT wall is not obtained, but solid‐state UV‐vis absorption profiles display electronic transitions fingerprinting J‐ and H‐ type aggregates, where porphyrin molecules intermolecularly interact “head‐to‐tail” and “face‐to‐face”, respectively. In parallel, molecular modeling based on force‐field simulations is performed to understand the structure of the porphyrin‐CNTs interface and the nature of the interactions between the porphyrins and the DWCNTs. Finally, multilayered‐type devices are fabricated with the aim of investigating the interaction of the porphyrin‐derived DWCNTs with poly(3‐hexylthiophene)‐pyrene matrices containing small amounts of 1‐[3‐(methoxycarbonyl)propyl]‐1‐phenyl‐[6.6]C61.

The segregation of As+ ions implanted into thin Er films deposited on n-Si substrates is studied after ErSi2-x formation. The same lowering of the effective Schottky barrier height (SBH) below 0.12 eV is obtained at moderate annealing temperatures, regardless of the redistribution of As dopants at the ErSi2-x/Si interface. On the other hand, if the implanted dose is slightly enhanced, the annealing temperature required to reach sub-0.12-eV effective SBH can be further reduced. This process enables the formation of very low effective SBH ErSi2-x/n-Si contacts with a low thermal budget.

The chemical changes of Ti/Er/n-Si(100) stacks evaporated in high vacuum and grown ex situ by rapid thermal annealing were scrutinized. The emphasis was laid on the evolution with the annealing temperature of (i) the Er-Si solid-state reaction and (ii) the penetration of oxygen into Ti and its subsequent interaction with Er. For that sake, three categories of specimens were analyzed: asdeposited, annealed at 300 degrees C, and annealed at 600 degrees C. It was found that the presence of residual oxygen into the annealing atmosphere resulted in a substantial oxidation of the Er film surface, irrespective of the annealing temperature. However, the part of the Er film in intimate contact with the Si bulk formed a silicide (amorphous at 300 degrees C and crystalline at 600 degrees C) invariably free of oxygen, as testified by x-ray photoelectron spectroscopy depth profiling and Schottky barrier height extraction of 0.3 eV at 600 degrees C. This proves that, even if Er is highly sensitive to oxygen contamination, the formation of low Schottky barrier Er silicide contacts on n-Si is quite robust. Finally, the production of stripped oxygen-free Er silicide was demonstrated after process optimization. (C) 2011 The Electrochemical Society. [DOI:10.1149/1.3585777] All rights reserved.

Submitted for the MAR10 Meeting of The American Physical Society Scanning Gate Microscopy on a Quantum Hall Interferometer FREDERICO MARTINS, BENOIT HACKENS, AUGUSTIN DUTU, VINCENT BAYOT, Universite Catholique de Louvain, Louvain-la-Neuve, Belgium, HERMANN SELLIER, SERGE HUANT, Institut Neel, Grenoble, France, LUDOVIC DESPLANQUE, XAVIER WALLART, IEMN, Villeneuve d’Ascq, France, MARCO PALA, IMEP-LAHC, MINATEC, Grenoble, France — We perform scanning gate microscopy (SGM) experiments [1] at very low temperature (down to 100 mK) in the Quantum Hall regime on a mesoscopic quantum ring (QR) patterned in an InGaAs/InAlAs heterostructure. Close to integer filling factors ν=6, 8 and 10,the magnetoresistance of the QR is decorated with fast periodic oscillations, with a magnetic field period close to AB/ν, where AB is the Aharonov-Bohm period. We analyze the data in terms of electron tunneling between edge states trapped inside the QR and those transmitted through the QR openings [2]. SGM images reveal that the tip-induced perturbation of the electron confining potential gives rise to a rich pattern of narrow and wide concentric conductance fringes in the vicinity of the QR. [1] F. Martins et al. Phys. Rev. Lett. 99 136807 (2007); B. Hackens et al. Nat. Phys. 2 826 (2006). [2] B. Rosenow and B. I. Halperin, Phys. Rev. Lett. 98, 106801 (2007). Frederico Martins Université Catholique de Louvain Date submitted: 09 Dec 2009 Electronic form version 1.4

SmallVolume 5, Issue 10 p. 1117-1122 Communication Towards All-Organic Field-Effect Transistors by Additive Soft Lithography† Dana Alina Serban, Dana Alina Serban CeRMiN, Université Catholique de Louvain Louvain-la Neuve 1348 (Belgium)Search for more papers by this authorPierpaolo Greco, Pierpaolo Greco CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via P. Gobetti 101, Bologna 40129 (Italy)Search for more papers by this authorSorin Melinte, Sorin Melinte CeRMiN, Université Catholique de Louvain Louvain-la Neuve 1348 (Belgium)Search for more papers by this authorAlexandru Vlad, Alexandru Vlad CeRMiN, Université Catholique de Louvain Louvain-la Neuve 1348 (Belgium)Search for more papers by this authorConstantin Augustin Dutu, Constantin Augustin Dutu CeRMiN, Université Catholique de Louvain Louvain-la Neuve 1348 (Belgium)Search for more papers by this authorStefano Zacchini, Stefano Zacchini Dipartimento di Chimica Fisica e Inorganica Università di Bologna, Bologna 40136 (Italy)Search for more papers by this authorMaria Carmela Iapalucci, Maria Carmela Iapalucci Dipartimento di Chimica Fisica e Inorganica Università di Bologna, Bologna 40136 (Italy)Search for more papers by this authorFabio Biscarini, Fabio Biscarini CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via P. Gobetti 101, Bologna 40129 (Italy)Search for more papers by this authorMassimiliano Cavallini, Corresponding Author Massimiliano Cavallini m.cavallini@bo.ismn.cnr.it CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via P. Gobetti 101, Bologna 40129 (Italy)CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via P. Gobetti 101, Bologna 40129 (Italy).Search for more papers by this author Dana Alina Serban, Dana Alina Serban CeRMiN, Université Catholique de Louvain Louvain-la Neuve 1348 (Belgium)Search for more papers by this authorPierpaolo Greco, Pierpaolo Greco CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via P. Gobetti 101, Bologna 40129 (Italy)Search for more papers by this authorSorin Melinte, Sorin Melinte CeRMiN, Université Catholique de Louvain Louvain-la Neuve 1348 (Belgium)Search for more papers by this authorAlexandru Vlad, Alexandru Vlad CeRMiN, Université Catholique de Louvain Louvain-la Neuve 1348 (Belgium)Search for more papers by this authorConstantin Augustin Dutu, Constantin Augustin Dutu CeRMiN, Université Catholique de Louvain Louvain-la Neuve 1348 (Belgium)Search for more papers by this authorStefano Zacchini, Stefano Zacchini Dipartimento di Chimica Fisica e Inorganica Università di Bologna, Bologna 40136 (Italy)Search for more papers by this authorMaria Carmela Iapalucci, Maria Carmela Iapalucci Dipartimento di Chimica Fisica e Inorganica Università di Bologna, Bologna 40136 (Italy)Search for more papers by this authorFabio Biscarini, Fabio Biscarini CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via P. Gobetti 101, Bologna 40129 (Italy)Search for more papers by this authorMassimiliano Cavallini, Corresponding Author Massimiliano Cavallini m.cavallini@bo.ismn.cnr.it CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via P. Gobetti 101, Bologna 40129 (Italy)CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN) Via P. Gobetti 101, Bologna 40129 (Italy).Search for more papers by this author First published: 07 May 2009 https://doi.org/10.1002/smll.200801732Citations: 25 † We thank Pablo Stoliar, Francesco Borgatti, and Radu Popa for their help and suggestions. This work was partly supported by ESF-EURYI DYMOT, Belgian F.R.S.-FNRS, and Wallonia Region. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Soft-processed organic transistors that exceed in performance compared to their counterparts made via standard microfabrication are demonstrated. The image shows the detail of an optical picture of the P3HT–Pt interface of an additively soft-patterned transistor, with Pt electrodes defined by MIMIC and P3HT stripes obtained by LCW. Citing Literature Supporting Information Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Filename Description smll_200801732_sm_suppdata.pdf141.2 KB suppdata Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. Volume5, Issue10May 18, 2009Pages 1117-1122 RelatedInformation

A highly sensitive pH capacitive sensor has been designed by confined growth of vertically aligned nanowire arrays on interdigited microelectrodes. The active surface of the device has been functionalized with an electrochemical pH transducer (polyaniline). We easily tune the device features by combining lithographic techniques with electrochemical synthesis. The reported electrical LC resonance measurements show considerable sensitivity enhancement compared to conventional capacitive pH sensors realized with microfabricated interdigited electrodes. The sensitivity can be easily improved by changing only the thickness of the functional layer.

Conductive polymers are a class of materials with vast potential for tomorrow's ultra-large-scale technologies as they combine structural and functional diversity with flexible synthesis and processing approaches. A missing component, with their subtle chemical structure, is reliable building at nanoscale. Here we report on the patterning of polyaniline, a prototypical conjugated polymer, with an unprecedented areal patterning order and density exceeding 0.25 teradot/inch(2). With template-confined growth, through platinum-surface-catalyzed polymerization of aniline, highly ordered arrays of distinct polyaniline nanowires are produced with a typical diameter <or=15 nm and aspect ratio higher than 20. Up-scaling is straightforward. Complex three-dimensional structural control is achieved through a direct pattern transfer via resist- and dose-modulated electron beam lithography. The morphology-modulated nanowires self-assemble in key-lock type architectures induced by the structure asymmetry and nonuniformity of the capillary forces associated with the re-entrant features.