Dynamic growth rate behavior of a carbon nanotube forest characterized by in situ optical growth monitoring

We characterize the dynamic growth rate behavior of a carbon nanotube (CNT) forest grown by means of optical interference phenomena. The CNT growth rate increased with an increase in CNT length at the initial stage and became stabilized after the CNT length was about 2 mum. Then the growth rate started to decelerate, passing the critical growth length in an almost linear manner. The termination length of the carbon nanotube was also precisely estimated by fitting the data of growth rate of carbon nanotubes to time. It was found that the CNTs show a transition from straight to curly nanotubes that is related to the decrease in the growth rate. The use of an in situ optical monitoring method has made possible the delicate length control of carbon nanotubes independent of the growth rate.