Tuning of diameter and electronic type of CCVD grown SWCNTs: A comparative study on Co-Mo and Co-Ru bimetallic catalyst systems

Wafer-level catalytic chemical vapour deposition (CCVD) of semiconducting enriched single-walled carbon nanotubes (sc-SWCNTs) with high quality is of high interest for industrial realization of SWCNT-based sensor and electronic applications. While bimetallic catalysts systems are known to favor type-enriched growth of SWCNTs, surface morphological evolution of different bimetallic catalyst stacks during catalyst conditioning as well as its impact on SWCNTs growth is not clearly understood. Here, we present a systematic study on the effect of bimetallic catalyst composition, layer stack thickness configuration as well as CCVD process parameters on the composition of grown SWCNTs. Besides the well-known Co and Co-Mo system, the Co-Ru system was investigated. We found that in case of Co-Mo bimetallic system, highest degree of sc-SWCNTs content is achieved using bilayer configuration Co-Mo:0.2–0.1 nm processed at 810 °C and 20 kPa total pressure. In case of Co-Ru bimetallic system, highest degree of sc-SWCNTs content is achieved using Co-Ru:0.1–0.1 nm processed at 840 °C and 10 kPa total pressure