Controlled growth of horizontally aligned single-walled carbon nanotubes

Abstract

Single-walled carbon nanotubes (SWCNTs) have native small size and outstanding electronic properties, which make them promising materials for building nanodevices. To realize their applications in nanoelectronics, it is necessary to control the length, alignment and density of these one-dimensional (1D) materials. This research is therefore motivated to investigate and evaluate the optimized growth procedures for the selective production of horizontally aligned SWCNT arrays on Si/SiOx substrates base on our local chemical vapor deposition (CVD) system. Variations of process parameters, including (1) catalyst composition, (2) catalyst patterning strategy and (3) synthesis temperature, were performed for SWCNTs synthesis by CVD. The results were analyzed and the growth process was improved in an attempt to increase the horizontally aligned SWCNTs yield. Studies revealed that both Co(acac)2 and “Needle Scratching” Method (NSM) induced catalyst could effectively assist the growth of SWCNTs by our ethanol CVD. The alignment of SWCNT arrays was improved by selective patterning of catalyst. Moreover, the influence of synthesis temperature on the SWCNTs alignment was discussed, the study revolved that higher synthesis temperature could better assist the SWCNTs alignment. Finally, an investigation was undertaken to elucidate the possible explanations to the morphology of SWCNTs that ended on the substrate surface away from edges. The tube-substrate interactions were to take the major responsibility for the wavy and entangled SWCNTs and their termination. Further research on scalable CVD growth of SWCNTs with better control over tube electrical properties and SWCNTs architecture are strongly recommended to improve the applicability and reliability of SWCNTs for large-scale fabrication of nanotube-based devices.