Arrays of horizontal semiconducting carbon nanotubes grown from non-metal catalysts prepared by a “thermophoresis-anchoring” synergistic strategy

The fabrication of uncontaminated single-walled carbon nanotube (SWNT) horizontal arrays is crucial for the development of carbon-based nanoelectronics. However, chemical vapor deposition (CVD) using transition metal catalysts, one of the main methods for preparing SWNT arrays, leaves a significant amount of metal impurities. Here, we report a synergistic thermophoresis-anchoring strategy to prepare uniformly dispersed and size-controllable non-metal SiO_x catalysts for the growth of horizontal SWNT arrays. The pyrolysis of silicon-based precursors generates an abundant supply of SiO_x particles, which are deposited bottom-up onto the quartz substrate due to the thermal buoyancy induced by a rapid temperature increase. Meanwhile, Surface reconstruction promoted by mechanical force creates numerous anchoring sites on the quartz substrate. This facilitates the capture of catalysts and suppresses their migration and aggregation, thereby promoting the uniform deposition of small-sized catalysts. Consequently, SWNT arrays with a density of 9 tubes per micron are synthesized using these nonmetal SiO_x catalysts. Importantly, Raman spectroscopy and electrical characterization reveal a semiconductor ratio of up to 94 % for the directly grown SWNT arrays, which is attributed to an in situ etching mechanism within the confined space. This work provides a viable way to promote the practical application of next-generation carbon-based nanodevices.