Long Length, High-Density Carbon Nanotube Film Grown by Slope Control of Temperature Profile for Applications in Heat Dissipation

Abstract

We have developed a new growth method for a film of dense, vertically aligned carbon nanotubes (CNTs). We varied the slope of the growth temperature profile between 450 and 800 °C. By using the method with an Fe/Ti catalyst, the filling factor of the CNT film was measured to be 0.28, which is 20 times denser than that in the case where conventional CVD growth is utilized. We name this growth method the slope control of temperature profile (STEP) growth. Another feature of CNT films obtained by STEP growth is their mirror like surfaces. This allows for the measurement of the thermal conductivity by a pulse optical heating thermoreflectance method. The maximum thermal conductivity of the STEP-grown CNT film was 260 W m-1 K-1, which is higher than those of a solder and Si. This result suggests that STEP-grown CNT films are effective heat dissipation materials and can be used as thermal interface material (TIM) and thermal through silicon via (TSV).

Facile preparation of carbon nanotube aerogels with controlled hierarchical microstructures and versatile performance

“…The total pore volume, average pore diameter and specific surface area of the prepared 9 CNT aerogels are summarized in Table 1. The above parameters of freeze-drying method prepared pure CMC monoliths are also given in Fig.…”

“…CNT-based materials include one-dimensional single CNT [1][2][3] and CNT fibers [4][5][6], two-dimensional CNT films [7][8][9][10][11] and three-dimensional CNT aerogels [12][13][14][15][16][17][18][19][20][21], which can be fabricated by chemical vapor deposition, suction filtration, critical-point-drying and so on. Specifically, CNT aerogels can be used for oil adsorption, insulation, energy storage and the fabrication of highly conductive polymer composites, due to the porous structures and the interconnected conductive networks [17,19,[22][23][24].…”

Low-temperature catalyst activator: mechanism of dense carbon nanotube forest growth studied using synchrotron radiation

“…In the improved process, we start to feed C 2 H 2 at 450 C and continue the feeding during the subsequent temperature elevation to 800 C. As a result, the CNT density obtained by this process was 20 times higher than that obtained by the conventional one where C 2 H 2 was supplied at 800 C (Kawabata et al, 2013). A high thermal conductivity of 260 W m À1 K À1 was also achieved for a grown CNT forest (Kawabata et al, 2013). We named the improved process 'STEP' as an abbreviation of 'slope control of temperature profile' (Kawabata et al, 2013).…”

“…A high thermal conductivity of 260 W m À1 K À1 was also achieved for a grown CNT forest (Kawabata et al, 2013). We named the improved process 'STEP' as an abbreviation of 'slope control of temperature profile' (Kawabata et al, 2013). The growth results suggest that, in the STEP process, catalyst activation and nanoparticle formation occurred at or near 450 C. However, this temperature seems unusually low to reduce oxidized Fe.…”

“…Recently, we developed an improved TCVD process that can densify CNTs without any pretreatments (Kawabata et al, 2013). We use Fe and Ti films with thicknesses of 2 and 1 nm as the catalyst layer and underlayer, respectively, which are deposited on a Si substrate.…”