CMOS Compatible Synthesis of Carbon Nanotubes

Abstract

A technique to synthesize high-quality single walled carbon nanotubes (SWNTs) using chemical vapour deposition (CVD) on Ge Stranski-Krastanow dots has been developed. From transmission electron microscopy and Raman measurements, the grown carbon nanotubes (CNTs) are identified as SWNTs with diameters ranging from 1.6 to 2.1 nm. Extensive scanning electron microscopy and atomic force characterisation of the effect of each stage in the growth process is presented. Our hypothesis is that pre-treatment stages lead to the formation of Ge nanoparticles, which act as seeds for CNT growth. This technique demonstrates the ability to synthesize high-quality SWNTs without the need for a metal catalyst, using processes and equipment standard to a silicon foundry.

Metal-Catalyst-Free Growth of Carbon Nanotubes for CMOS Integration

“…1(a). Similar nanowires were seen in our earlier work and were composed mainly of silica [7], [9]. In contrast, an additional Ar annealing process dramatically aids CNT growth, giving an area density of 3.0 CNTs/µm 2 .…”

“…Several different metal-catalyst-free growth methods of CNTs have been reported [5][6][7][8][9]. However none of the growth methods can grow single walled CNTs (SWNTs) on SiO 2 for device applications.…”

Chemical Vapour Deposition of CNTs Using Structural Nanoparticle Catalysts

“…Instead, a reduction of the GeO 2 around the single crystalline core of the non-oxidized Ge dot materials results in only Ge-enriched clouds, surrounded by a matrix of non-reductible material. This assertion is supported by SEM images taken after each stage in the process (not shown), which indicate a definite change of morphology after the chemical oxidation and reduction steps (Uchino et al, 2008). In fact, there have been reports of the formation of ultra-high density Ge nanoparticles, with diameters of about 4 nm, from the oxidation/reduction of Ge/Si surfaces (Nakamura et al, 2004), which further supports this hypothesis.…”

Highly Anisotropic Polymer Composites Based on Carbon Nanotubes

“…Nanoparticles of transition metals (Fe, Ni and Co) are usually used for the catalytic growth of CNT [22]. Recently, CNT has also been produced from precious novel metal [23][24][25][26][27], catalysts based on ceramic nanoparticles [28,29] and semiconductor nanostructures [30][31][32][33]. This work has led to a new interpretation of the role of the catalyst in growth of nanotubes in which sites of adsorption of carbon are necessary for fixing the nanodimensional curvature.…”