Keywords: nanomaterials, carbon nanotubes, photothermal chemical vapor deposition, low temperature growth 2 For carbon nanotubes (CNTs) to be exploited in electronic applications the growth of high quality material on conductive substrates at low temperatures (< 450 o C) is required. CNT quality is known to be strongly degraded when growth is conducted on metallic surface at low temperatures using conventional chemical vapor deposition (CVD). Here, we demonstrate production of high quality vertically-aligned CNTs at low substrate temperatures (350 -440 o C) on conductive TiN thin film using photo-thermal CVD by confining the heat required for growth to just the catalyst using an array of optical lamps and by optimizing the thickness of the TiN under-layer. The thickness of the TiN plays a crucial role in determining various properties including diameter, material quality, number of shells and metallicity. The highest structural quality with a visible Raman D-to G-band intensity ratio as low as 0.13 is achieved for 100 nm TiN thickness grown at 420 o C; a record low value for low temperature CVD grown CNTs. Electrical measurements of high density CNT arrays show the resistivity to be 1.25×10 -2 Ωcm represents some of the lowest values reported. Finally, the broader aspects of using this approach as a scalable technology for carbon nanomaterial production are also discussed.3

A study of graphene on metal nanotextured surfaces for ultra-broadband light trapping, blackbody absorbers, and thermal imaging.

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The synthesis of high quality nanomaterials depends on the efficiency of the catalyst and the growth temperature. In order to produce high quality material high growth temperatures

Despite the “darker than black” association attributed to carbon nanotube forests, here is shown that it is also possible to grow these structures, over heat‐sensitive substrates, featuring highly transmissive characteristics from the UV to infrared wavelengths, for forest heights as high as 20 μm. The optical transmission is interpreted in terms of light propagation along channels that are self‐generated by localized bundling of tubes, acting as waveguides. A good correlation is shown between the distribution of diameter sizes of these sub‐wavelength voids and the transmission spectrum of the forests. For the shorter visible and near‐UV wavelengths, this model shows that light propagates by channeling along individual vertical voids in the forests, which elucidates the origin for the widely‐reported near‐zero reflectance values observed in forests. For the longer infrared wavelengths, the mode spreads over many nanotubes and voids, and propagates along a “homogeneous effective medium”. The strong absorption of the forest at the shorter wavelengths is correlated in terms of the stronger attenuation inside a waveguide cavity, according to the λ−1/2 attenuation dependency of standard waveguide theory. The realization of this material can lead to novel avenues in new optoelectronic device design, where the carbon nanotube forests can be used as highly conducting “scaffolds” for optically active materials, whilst also allowing light to penetrate to significant depths into the structure, in excess of 20 μm, enabling optical functionality.

Semiconducting nanostructures such as nanowires (NWs) have been used as building blocks for various types of sensors, energy storage and generation devices, electronic devices and for new manufacturing methods involving printed NWs. The response of these sensing/energy/electronic components and the new fabrication methods depends very much on the quality of NWs and for this reason it is important to understand the growth mechanism of 1D semiconducting nanostructures. This is also important to understand the compatibility of NW growth steps and tools used in the process with these unconventional substrates such as plastic that are used in flexible and large area electronics. Therefore, this Element presents at length discussion about the growth mechanisms, growth conditions and the tools used for the synthesis of NWs. Although NWs from Si, ZnO and carbon nanotubes (CNTs) are included, the discussion is generic and relevant to several other types of NWs as well as heterostructures.

We introduce a combined process for the reduction of graphene oxide (GO) via vitamin C (ascorbic acid) and thermal annealing.

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