Local Current Mapping and Patterning of Reduced Graphene Oxide Jeffrey M. Mativetsky, † Emanuele Treossi, ‡ Emanuele Orgiu, † Manuela Melucci, ‡,§ Giulio Paolo Veronese, | Paolo Samorı `,* ,† and Vincenzo Palermo* ,‡ Nanochemistry Laboratory, ISIS - CNRS 7006, UniVersite ´ de Strasbourg, 8 alle ´e Gaspard Monge, 67000 Strasbourg, France, Istituto per la Sintesi Organica e la FotoreattiVita `- Consiglio Nazionale delle Ricerche, Via Gobetti 101, 40129 Bologna, Italy, Istituto di Chimica dei Composti Organometallici - Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto F.no (Fi), Italy, and Istituto per la Microelettronica e i Microsistemi - Consiglio Nazionale delle Ricerche, Via Gobetti 101, 40129 Bologna, Italy Received May 26, 2010; E-mail: samori@unistra.fr; palermo@isof.cnr.it Abstract: Conductive atomic force microscopy (C-AFM) has been used to correlate the detailed structural and electrical characteristics of graphene derived from graphene oxide. Uniform large currents were measured over areas exceeding tens of micrometers in few-layer films, supporting the use of graphene as a transparent electrode material. Moreover, defects such as electrical discontinuities were easily detected. Multilayer films were found to have a higher conductivity per layer than single layers. It is also shown that a local AFM-tip-induced electrochemical reduction process can be used to pattern conductive pathways on otherwise-insulating graphene oxide. Transistors with micrometer-scale tip-reduced graphene channels that featured ambipolar transport and an 8 order of magnitude increase in current density upon reduction were successfully fabricated. Introduction Graphene possesses unique electrical properties on account of its single-atom-thick two-dimensional honeycomb lattice structure. 1,2 Charge carriers act as massless Dirac fermions; 3 perturbations in the sheet lead to charge puddles, 4 and remark- able electron and hole mobilities result from the zero-gap semiconductor band structure. 3 Moreover, its high conductivity and optical transparency over visible wavelengths make graphene a candidate for large-area electrode applications such as solar cells and displays. 5-8 While rapid progress in measuring electrical transport in multilayer films and single graphene sheets has been achieved, little is known about the local spatial dependence of the electrical properties. Here we show that conductive atomic force microscopy (C-AFM) 9 is a powerful tool for obtaining direct measurements of the local variations in current-carrying capacity in graphene sheets and films over length scales ranging from tens of nanometers to tens of micrometers. These measurements make it possible to correlate the detailed morphology of graphene (e.g., wrinkles, multilayer regions) to its electrical characteristics. It is further demonstrated that a metallic AFM tip can be used to pattern electrically insulating graphene oxide (GO) with micrometer-scale conduc- tive regions. The conversion of GO to graphene through chemical reduc- tion or thermal treatment is widely viewed as a promising pathway to mass production. 5,6,10-13 GO sheets consist of a graphitic carbon network bearing various types of oxygen- containing defects that render the sheets soluble in water. This allows the efficient processing and dispersion of isolated sheets or multilayer films from solution. 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AM. CHEM. SOC. 2010, 132, 14130–14136