Characterization of thermal transport and laser absorption properties of an individual pristine SWCNT

Abstract

Determination of thermal transport properties and optical absorption cross-section of nanowires is of central importance for designing nano-optoelectronics and nano-photovoltaics. Experimental study of these properties is challenging because of the very small size of a typical sample. In this study, we present a steady-state Raman method for determining the temperature (T)-dependent thermal conductivity (λ) and laser absorption cross-section (Cabs) for an individual nanowire. This method was verified and then applied to determine λ and Cabs of an individual pristine single-walled carbon nanotube (SWCNT, L = 22 μm, d = 1.29 nm). The results show that λ decreases with increasing T in this experimental temperature range, indicating that higher temperature induces a larger scattering rate of three-phonon Umklapp processes. By measuring the temperature increase at the sample center induced by a 0.284 mW focused polarized Gaussian laser spot (514.5 nm, re = 1.0 μm), we derived the absorbed laser power (Pα) and Cabs to be 3.98 × 10−5 mW and 5.46 × 10−15 m2 for this individual SWCNT. The laser absorption cross-section per carbon atom (σc) was determined to 1.64 × 10−17 cm2 with an uncertainty lower than 10.6%.