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ABSTRACT: In the present work we report a simple method to fabricate Si nanotubes (NTs) starting from the growth of self-assembled sacrificial Si nanowires that, at the same time, embeds them into a polyimide matrix, allowing a very easy manipulation of these nano-objects, including removal, transfer and positioning. Our all-silicon fabrication method is completely compatible with the Si technology platform and is therefore implementable using the existing technology. Transferred NTs show good electrical contact with underlying electrodes, and relatively low resistance values have been measured. All these features demonstrate the effectiveness of the transfer method and the potentiality of the NTs in electronics. Finally, optical reflectivity of the NTs has been measured in the near UV-near IR spectral range.
Nanotechnology 08/2012; 23(30):305602. · 3.98 Impact Factor
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Journal of Applied Physics 01/2012; 111(11):114302. · 2.17 Impact Factor
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ABSTRACT: We report a very simple, robust, and reliable on-chip fabrication method of a chemoresistive sensor
based on silicon nanowires (NWs). Our method permits the use of nanowires without the need of
their removal and transfer to a support different from the growth substrate. Our method, completely
based on the silicon technology platform, exploits nanowires directly grown onto a selected area,
over and between pre-patterned, interdigitated electrodes defined on oxidized silicon. The
fabricated sensor is capable to detect NO2 down to a few ppb levels operating at room temperature.
The sensor characteristics benefit of the presence of self-welded nanowires.
Applied Physics Letters 01/2012; 101:103101. · 3.84 Impact Factor
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Journal of Crystal Growth 01/2011; 335(1):10. · 1.73 Impact Factor
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ABSTRACT: In this work we present a study of the reflectivity from highly disordered silicon nanowire films as a function of the wire size. Arrays of Au-catalyzed Si wires with length and diameter ranging from 0.15-0.2 microm and 30-50 nm up to 20-25 microm and 200-250 nm, respectively, were grown on top of either SiO(2)(1 microm)/Si(100) or Si(100) substrates. The integrated total reflection was measured in the 190-2500 nm spectral range. The results show that, increasing the wire size, the optical behavior of the Si wire film can be gradually tuned from that of an optical coating characterized by a graded effective refractive index to that of an ensemble of diffuse optical reflectors. In addition, we show how the optical analysis provides some important indications concerning the structural properties of the nanowires.
Nanotechnology 09/2010; 21(35):355701. · 3.98 Impact Factor
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ABSTRACT: High densities of self-catalyzed Si nanowires have been grown at temperatures down to 320 degrees C on different Si substrates, whose surfaces have been roughened by simple physical or chemical treatments. The particular substrates are Si(110) cleavage planes, chemically etched Si(111) surfaces and microcrystalline Si obtained by laser annealing thin amorphous Si layers. The NW morphology depends on the growth surface. Transmission electron microscopy indicates that the NWs are made of pure Si with a crystalline core structure. Reflectivity measurements confirm this latter finding.
Nanotechnology 06/2010; 21(25):255601. · 3.98 Impact Factor
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ABSTRACT: Indium-assisted silicon nanowires have been grown by plasma enhanced chemical vapor deposition at temperatures down to 330 °C without plasma pre-treatment of the In films deposited on silicon substrates before the growth. Two families of wires have been observed: thin, tapered wires that show a metallic nanoparticle at their top, and thick, almost cylindrical wires that have no metallic nanoparticle at their final end. We suggest that the two types of NWs grow after different mechanisms. Moreover, we point out important growth features that are common with Au- and self-induced nanowires.Highlights► Indium was used to induce low-temperature growth of Si nanowires. ► Two types of Si nanowires are observed: with or without In nanoparticles on top. ► Two types of nanowires grow after different mechanisms. ► The lowest growth temperature is the same for In-, Au- and self-induced Si nanowires.
Journal of Crystal Growth 335(1):10-16. · 1.73 Impact Factor
