Phases of Carbon Nanotube Growth and Population Evolution from in Situ Raman Spectroscopy during Chemical Vapor Deposition

Abstract

The dynamical evolution of nanotube chemical vapor deposition growth was investigated by in situ spectroscopy of three main Raman bands: G, D, and RBM. The evolution in diameter distribution is inferred from RBM and G bands, and the evolution in crystallinity is determined from D and G bands. A consistent sequence of the growth evolution is observed, with four discernible phases: incubation, acceleration, linear growth, and termination. The temperature dependence of each of these stages of growth is experimentally determined, and characteristic energy scales apparently associated with each phase are extracted. The growth becomes slower as the temperature increases, with activated, parasitic reactions suggested as a cause. We explore to what extent one diameter grows in comparison to another and thus gain some insight into how the nanotube population changes with time.

Type- and Species-Selective Air Etching of Single-Walled Carbon Nanotubes Tracked with in Situ Raman Spectroscopy

“…A challenge for such measurements is background subtraction, which can be a large source of error in the evolution curves. For background subtraction, we employed a simple trapezoidal background correction algorithm, described in previous work 65 and illustrated in the SI. As described above the integrated intensities were further normalized against the first-order Si band to compensate for any drift in illumination intensity or collection efficiency.…”

Data-driven understanding of collective carbon nanotube growth by in situ characterization and nanoscale metrology

“…[77][78][79] Also, in situ Raman spectroscopy can be used to provide a measure of relative mass kinetics from real-time integration of the area under the G-band. [80][81][82][83] Real-time monitoring of the G-band during growth of single-wall CNTs was instrumental in demonstrating that the growth rate is dependent on CNT chirality. 84 Recently, in situ electron energy loss spectroscopy (EELS) was used to quantify the accumulating carbon on the surface during CNT growth inside E-TEM, by plotting the time evolution of the carbon K-edge nearedge structure.…”

From Nanotechnology to Nanoengineering

“…In this regard, knowing process kinetics and the related issue of mechanisms are a necessary prelude to model and control changes in progress (Texter and Tirrell 2001). Observing the evolution of processes necessitates acquisition of accurate kinetic data in real time, and hence, researchers put their attention toward developing in situ measurement of nanostructure during their formation process to observe and control changes in progress (Zhao et al 2003;Puretzky et al 2005;Li-Pook-Than et al 2010). The acquisition of such data will impel development of a sophisticated instrumentation that provides informative, online measurement to observe and control changes in progress.…”