Ultra-short-pulse laser ablation and modification of fully sprayed single walled carbon nanotube networks
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In this study, we report on femtosecond (470 fs) laser pulse ablation and modification of solution processed single-walled carbon nanotube (SWCNT) networks sprayed on oxidized silicon and polyimide substrates. Taking advantage of the small heat affected zone of the femtosecond pulse regime we demonstrate precise and selective laser processes, that advance laser patterning beyond simple galvanic isolation. A thorough investigation regarding the laser pulse-SWCNT film interaction is performed, identifying critical interaction regimes in the single- and multi-pulse operation mode. For the first time we achieve a pronounced debundling of the network, by operating the laser below the ablation threshold, a process that was previously limited to pre-deposition. Furthermore, we investigate the effect of polarized laser pulses on the ablation properties. Making use of linear polarized laser pulses we are able to selectively ablate SWCNTs, which are oriented parallel to the incident laser polarization, resulting in aligned networks with anisotropic conductivity. This feature was previously tied to direct growth of SWCNTs, strongly limiting its implementation. The scaleability of the presented femtosecond laser processes is demonstrated, allowing for the use of low-cost solution processed SWCNT thin-films, while maintaining the advantages of on-chip SWCNT growth such as SWCNT separation and alignment. (C) 2018 The Authors. Published by Elsevier Ltd.