In recent years, a large amount of research has been applied to structuring materials in the form of nanowires, nanotubes and nanocrystals. In silicon, [1] zinc-oxide [2] and carbon [3] this has led to greatly enhanced material properties [4,5] and to the development of new superstrong composite materials, [6] high performance 1D nanowire field effect transistors [7] and ultrasensitive chemical and biological sensors.[1] Conducting polymers have also been synthesized in the form of fibers, tubes and wires at the micro-and nano-length-scales. [8][9][10] Although this has been possible for more than 10 years, it is only recently that new fabrication techniques [11][12][13][14][15][16][17] have allowed the integration of nanowires into microelectronic circuits, making possible the development of devices such as polymer nanowire chemical sensors with superior performance. [14,15,[18][19][20] These fabrication techniques mostly rely on templates, such as lithographically-defined nanochannels, [11,12] DNA templates, [15] or the use of specialized fiber/wire forming techniques, such as electrospinning [13,14,21] to control the growth and structure the polymer into the desired form. In contrast, our work focuses on the development of nanowire devices using template-free conditions. Our approach is motivated by the natural tendency of some conducting polymers to form as nanowires during synthesis, which could greatly simplify the process of nanowire device fabrication. In this communication we demonstrate a method that allows a controlled number of highly aligned conducting polymer nanowires to be grown between two nanometer-scale metal electrodes, thereby providing a simple way to incorporate single and multiple nanowires into pre-patterned electrical circuits. Since the nanowires are grown within the device and electrical connections are made in situ during the growth process, the technique avoids the time-consuming and challenging task of manipulating nanowires into position and making electrical contacts post-synthesis. The versatile nature of the technique is shown by the progressive transition in dimensionality of devices consisting of 1) planar 3D ordered nanowire arrays bridging 500 nm junctions to 2) a linear 2D ordered nanowire array, and ultimately, 3) a single 1D ordered nanowire-bridge. A highly sensitive nanowire chemical sensor has been fabricated as a proof-ofconcept of this method and we report results concerning the exposure of the sensor to ammonia gas.Conducting polymers such as polypyrrole, polyaniline, and polythiophene have been intensively studied for use in biochemical and chemical sensors [22][23][24][25][26] because they are chemically active materials that respond, either electronically or optically, when exposed to a wide range of different gases. They are well suited to chemical functionilization, and may thus be tailored towards the detection of specific analytes (see for example glucose sensors [27] and detection of DNA hybridization [28] ). Of increasing importance is their ability to be s...

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The Curie temperature of the residual amorphous phase in nanocrystalline Fe89Zr7B3Cu1 is enhanced by Ge addition and the magnetic hardening at elevated temperatures is suppressed. On the other hand, the addition of Co brings about severe deterioration of the magnetic softness for the same alloy presumably because of the induced anisotropy effect. The Mössbauer and atom probe field ion microscopy analyses indicate that Ge-induced magnetic softening is due to the preferential enrichment of Ge into the residual amorphous phase which results in an enhancement of the exchange stiffness in the intergranular region.

We report the development of nanowire field-effect transistors featuring an ultrathin parylene film as a polymer gate insulator. The room temperature, gas-phase deposition of parylene is an attractive alternative to oxide insulators prepared at high temperatures using atomic layer deposition. We discuss our custom-built parylene deposition system, which is designed for reliable and controlled deposition of <100 nm thick parylene films on III-V nanowires standing vertically on a growth substrate or horizontally on a device substrate. The former case gives conformally coated nanowires, which we used to produce functional Ω-gate and gate-all-around structures. These give subthreshold swings as low as 140 mV/dec and on/off ratios exceeding 10 at room temperature. For the gate-all-around structure, we developed a novel fabrication strategy that overcomes some of the limitations with previous lateral wrap-gate nanowire transistors. Finally, we show that parylene can be deposited over chemically treated nanowire surfaces, a feature generally not possible with oxides produced by atomic layer deposition due to the surface "self-cleaning" effect. Our results highlight the potential for parylene as an alternative ultrathin insulator in nanoscale electronic devices more broadly, with potential applications extending into nanobioelectronics due to parylene's well-established biocompatible properties.

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