Self-assembled carbon nanotubes grown without catalyst from nanosized carbon particles adsorbed on silicon

Botti, S.; Ciardi, R.; Terranova, Maria Letizia; Piccirillo, S.; Sessa, V.; Rossi, M.; Vittori‐Antisari, M.

doi:10.1063/1.1453485

Cited by 31 publications

(20 citation statements)

References 7 publications

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“…This technique also depends on the structural reorganization of carbon aggregates into nanotubes upon annealing. Botti et al [20] report a dense array of CNTs grown on silicon by spraying amorphous hydrogenated carbon nanoparticles on a Si substrate and annealing. Other similar approaches have been reported in the literature [21].…”

Section: Catalyst Free Synthesis Of Cntsmentioning

confidence: 99%

On the mechanism of carbon nanotube formation: the role of the catalyst

Ayre

Uchino

Mazumder

et al. 2011

J. Phys.: Condens. Matter

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This work examines the recent developments in non-traditional catalyst-assisted chemical vapour deposition of carbon nanotubes (CNTs) with a view to determining the essential role of the catalyst in nanotube growth. A brief overview of the techniques reliant on the structural reorganization of carbon to form CNTs is provided. Additionally, CNT synthesis methods based upon ceramic, noble metal, and semiconducting nanoparticle catalysts are presented. Experimental evidence is provided for CNT growth using noble metal and semiconducting nanoparticle catalysts. A model for CNT growth consistent with the experimental results is proposed, in which the structural reorganization of carbon to form CNTs is paramount.

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Section: Catalyst Free Synthesis Of Cntsmentioning

confidence: 99%

On the mechanism of carbon nanotube formation: the role of the catalyst

Ayre

Uchino

Mazumder

et al. 2011

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

“…This technique depends on the structural reorganization of carbon aggregates into nanotubes upon annealing. Botti et al (2002) report a dense array of CNTs grown on silicon by spraying amorphous hydrogenated carbon nanoparticles on a Si substrate. Other similar approaches have been reported in the literature (Koshio et al, 2002;Larciprete et al, 2002;.…”

Section: Catalyst Free Synthesis Of Cntsmentioning

confidence: 99%

Chemical Vapour Deposition of CNTs Using Structural Nanoparticle Catalysts

Ayre¹,

Uchino²,

Mazumder³

et al. 2010

Carbon Nanotubes

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“…Several different metal-catalyst-free growth methods of CNTs have been reported, [6][7][8][9][10][11][12] including our earlier work on CNT growth from Ge nanoparticles. 8,10 However to date, no device results have been reported for CNTFETs produced by any of the metal-catalyst-free CNT growth methods, mainly because it has not been possible to grow CNTs on a suitable insulator without a metal catalyst.…”

mentioning

confidence: 99%

Metal-Catalyst-Free Growth of Carbon Nanotubes and Their Application in Field-Effect Transistors

Uchino¹,

Ayre²,

Smith³

et al. 2011

Electrochem. Solid-State Lett.

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Abstract:The metal-catalyst-free growth of carbon nanotubes (CNTs) using chemical vapor deposition and the application in field-effect transistors (FETs) is demonstrated. The CNT growth process used a 3-nm-thick Ge layer on SiO 2 that was subsequently annealed to produce Ge nanoparticles. Raman measurements show the presence of radial breathing mode peaks and the absence of the disorder induced D-band, indicating single walled CNTs with a low defect density. The synthesized CNTs are used to fabricate CNTFETs and the best device has a state-of-the-art on/off current ratio of 3×10 8 ExperimentalA p + Si substrate (0.005 Ω·cm) was employed as a back gate and a 45-nm-thick thermally grown SiO 2 layer was employed as a gate dielectric. A 3-nm-thick Ge layer was deposited by either sputtering or evaporation on the SiO 2 layer. The nanoparticles on the insulator were formed at 850°C for 10 min in a mixture of Ar (1000 sccm) and H 2 (300 sccm) after a preanneal in H 2 (1000 sccm) at 950°C. The samples were reloaded to a hot-wall reactor and then CNT growth was performed using chemical vapor deposition (CVD) at atmospheric pressure.CNTs were grown at 850°C for 10 min using a mixture of methane (1000 sccm) and H 2 (300 sccm) immediately after a pre-anneal in H 2 (1000 sccm) at 900°C. Back gate CNTFETs were fabricated with Pd source/drain contacts. Pd was deposited by sputtering and the source/drain electrodes were formed using direct write laser lithography and lift-off. The gap between Pd source/drain electrodes was 2.0 µm and the width was 8.0 µm. Typically only one or two CNTs crossed over the 2.0 µm gap between the source and drain. Electrical characteristics of CNTFETs were measured in ambient air. Raman spectra were obtained using He-Ne (632.8 nm) laser excitation. Figure 1a shows the particle height distribution after nanoparticle formation obtained from atomic force microscopy (AFM) measurements. Line analysis shows that the peak particle count occurs at a particle height of 1.4 ± 0.8 nm and area analysis gives a mean particle density of 450 ± 20 particles/µm 2 . Figure 1b shows a typical field emission scanning electron microscope (FE-SEM) image after CNT growth. CNTs can clearly be seen, together with shorter and thicker nanowires, which have been shown to be silica nanowires in our 3 earlier work. 8,10 The area density of CNTs was analyzed using several FE-SEM images from different parts of the wafer and evaluated as 3.0 CNTs/µm 2 . Results and DiscussionEnergy dispersive X-ray spectroscopy analysis indicates that the nanoparticles contain a mixture of Ge, Si, and O. 13 In order to investigate the origins of the oxygen, CNTs were grown without air exposure after the Ar/H 2 anneal. The observed area density of CNT was 3.4CNTs/µm 2 , compared with 3.0 CNTs/µm 2 after air exposure, which indicates that air exposure has no significant effect. This result suggests that the oxygen in the nanoparticles comes from the SiO 2 substrate in this case. These and earlier results 11,12 suggest the following mechanism for CNT...

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Self-assembled carbon nanotubes grown without catalyst from nanosized carbon particles adsorbed on silicon

Cited by 31 publications

References 7 publications

On the mechanism of carbon nanotube formation: the role of the catalyst

On the mechanism of carbon nanotube formation: the role of the catalyst

Chemical Vapour Deposition of CNTs Using Structural Nanoparticle Catalysts

Metal-Catalyst-Free Growth of Carbon Nanotubes and Their Application in Field-Effect Transistors

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