(Invited) Shedding Light on the Growth Kinetics of Individual Carbon Nanotubes Using in Situ Optical Microscopy

Abstract

Growing single-walled carbon nanotubes (SWCNTs) with high selectivity for specific chiralities is a matter of intense research activity with important implications in the fields of electronic and optoelectronic devices. However, a fundamental understanding of the dependence of each growth step (nucleation, elongation, chirality change, termination) on the nanotube chirality is still missing to allow a rational design of highly selective growth methods. In this presentation, we will show how a newly developed method of optical imaging [1,2] allows the in situ observation of individual SWCNTs in real conditions of growth (i.e. at atmospheric pressure on a substrate) and with time resolution down to a few tens of ms. Based on these observations, we will report on the dependence of the growth kinetics (rate, lifetime) of individual SWCNTs on the growth conditions (temperature, carbon supply) and on the SWCNT chirality (diameter, chiral angle). We will also report a comprehensive method to model the optical spectra of individual SWCNTs on substrate obtained with the same polarization-based setup [2]. Importantly, this model includes the influence of the commonly used anti-reflection substrates (e.g. SiO2/Si), and of coherent and non-coherent depolarization by the optics. This model allows extracting both the real and imaginary parts of the nanotube susceptibility and improving the chirality assignment when coupled with complementary techniques such as Raman spectroscopy.[1] Liu et al, Nature Nanotechnology (2013), 8, 917.[2] Comprehensive model of the optical spectra of carbon nanotubes on a substrate by polarized microscopy, L. Monniello, H.-N. Tran, R. Vialla, G. Prévot, S. Tahir, T. Michel, V. Jourdain, Physical Review B (2019), 99, 115431. Figure 1