Electrochemical synthesis of a ZnO nanowire field-effect transistor
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0951-E08-05
Electrochemical Synthesis of a ZnO Nanowire Field-Effect Transistor Travis Lee Wade Laboratoire des Solides Irradies, ECOLE Polytechnique, Route de Saclay, Palaiseau, 91128, France ABSTRACT Aluminum wires are electrochemically sculptured into bi-directional templates for the growth and contacting of nanowires as three terminal devices. The utility of this nanostructured microtemplate is demonstrated by a ZnO nanowire surrounding gate field-effect transistor. This bottom-up approach to a 3-D nanowire transistor is unique in that it can be almost entirely fabricated in a beaker using aqueous, room-temperature electrochemistry. INTRODUCTION There are many elegant chemical and physical routes to nanowires and nanodots. Electrodeposition, sol-gel synthesis, and CVD are but a few of the techniques that can produce nanostructures with nanometer control.[1-5] The quality and reproducibility of these nanostructures are well developed. The difficulty is, however, to organize and contact these nano-objects.[6, 7] This is when nanoporous templates are useful. The role of the template is two fold. First, it allows the production of the structure with the best possible reproducibility and it plays the role of a skeleton in order to organize the different functions of a device, the active components and the different interfaces (building blocks, electric contacts, gate voltage, bias fields, and optical sensors) on a rigid body. Second, this nanoscaffold is used to link the structure to the macroscopic world. With template synthesis it is possible to identify three different steps: (1) the creation of the building blocks, the nanowires or nanodots, (2) the assembly of the nano building blocks into a functional architecture within the template, and (3) the fabrication and control of the contacts to the macroscopic world. The first and second steps coincide for metallic nanowires or semiconductors that are made by electrodeposition. For carbon nanotubes and silicon nanowires a catalytic layer is made by electrodeposition followed by CVD for the carbon nanotubes or solid-liquid-vapor growth for the silicon nanowires. The final step, and perhaps most important, is the contact of the nanoscale objects to the macroscopic world. Porous alumina is commonly used as a template for nanowire synthesis.[8] It is made by anodization of aluminum in acidic solutions, which forms a self-assembled, hexagonal network of nanometer diameter pores.[9-13] These are desirable templates because the pore diameter, distribution, and pore length can be tailored to suit the needs of the user by varying the anodization conditions: electrolyte, voltage, time, and temperature. The chosen pore size determines the resulting nanowire dimensions. Another advantage is that once the nanowires have been made in the alumina template, they can be electrically contacted at the top and bottom of the membrane for physical measurements without the need for lithography. Thus, the template acts as a scaffold or mould for the nanowires. The standard template approac
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