Chemical vapor deposition-grown vertically aligned single-walled carbon nanotubes length assurance

Abstract

Chemical vapor deposition is one of the several viable methods for growing vertically aligned single-walled carbon nanotubes (VA-SWNTs). Utilizing cobalt (Co) catalyst supported on multilayer Al/SiO2 and a hydrocarbon feedstock, VA-SWNTs are grown in excess of a millimeter height. To control VA-SWNTs length, one has to use the right combination of process control variables such as hydrocarbon gas flow rate, chamber temperature, and chamber pressure. This paper presents a process meta-model-based full factorial experimental design and analysis to study the yield of tall VA-SWNTs. All of the process variables under the study play a role in influencing VA-SWNTs length; the current study investigates main effects and their interactions. The meta-model-based analysis demonstrates that the hydrocarbon flow rate and the chamber pressure are the most statistically significant control variables that influence the length of VA-SWNTs. In addition, the response surface graph confirms that a higher gas flow rate at lower chamber pressure will consistently yield tall VA-SWNTs. We found that gas flow rate is the most significant of the control variables and only the optimum gas flow rate can ensure the growth of tall VA-SWNTs. We noticed that the interaction of gas flow rate with chamber temperature is also significant to the length of VA-SWNTs grown. All these observations together indicate that the dynamic pressure of the gas in the chamber plays an important role in the assurance of the length of VA-SWNTs. Outcomes of this investigation are beneficial for moving us closer towards producing VA-SWNTs on a mass scale.