Express determination of thickness and dielectric function of single-walled carbon nanotube films

Abstract

Single-walled carbon nanotube (SWCNT) films are promising building blocks for diversified applications in electronics, photovoltaics, and photonics. However, their electrical and optical engineering is still a challenging task owing to multiple obstacles, including the absence of fast and easy-to-use methods for the determination of SWCNT film properties. Here, we present a rapid, contactless, and universal technique for accurate estimation of both SWCNT film thicknesses and their dielectric functions. The approach combines broadband optical absorbance and highly sensitive spectroscopic ellipsometry measurements. The observed linear dependence of the film thickness on its absorbance at 550 nm provides a time-effective and contactless method of thickness assignment, which is of significant importance to the practical implementation of SWCNT films in optoelectronic devices. Additionally, our approach revealed that a simple procedure of film densification allows to controllably alter the dielectric response by at least 40% and, thus, to add extra fine-tuning capabilities during material property engineering. Therefore, this express technique as a whole offers an advanced metrological tool for current and next-generation SWCNT-based devices.

Optical Constants of Chemical Vapor Deposited Graphene for Photonic Applications

“…Interestingly, graphene’s optical response is similar in shape to other carbon materials such as graphite [ 39 ] and single-walled carbon nanotube (SWCNT) films [ 40 ], as illustrated in Figure 3 . More importantly, the optical constants of graphene are almost identical to graphite.…”

“…We calculated the transmittance spectrum based on retrieved optical constants, which is in good agreement with the experimental one as illustrated in Figure 2e, thereby validating the acquired dielectric function. Interestingly, graphene's optical response is similar in shape to other carbon materials such as graphite [39] and single-walled carbon nanotube (SWCNT) films [40], as illustrated in Figure 3. More importantly, the optical constants of graphene are almost identical to graphite.…”

“…The data of Nelson, Li, Graphite, and SWCNT film are adopted from refs. [ 26 , 29 , 39 , 40 ], respectively.…”

“…Comparison of the measured (red lines) refractive index n (a) and extinction coefficient k (b) and some previous results for CVD graphene on glass (blue lines) and quartz (green lines) substrates obtained without any assumptions in the ellipsometric model and carbon materials such as graphite (dashed lines) and SWCNT film (dotted lines). The data of Nelson, Li, Graphite, and SWCNT film are adopted from refs [26,29,39,40],. respectively.…”

Influence of Particle Size Distribution on the Optical Properties of Fine-Dispersed Suspensions

“…First, using the conventional approach based on Mie scattering theory, we determine the extinction spectra of the nanofluid of known composition as a function of particle diameter. The optical properties required for calculations, namely real and imaginary parts of the complex refractive index, can be found elsewhere [44,45]. Second, the derived expression for extinction spectra is averaged over volumetric particle size distribution, obtained via experimental measurement.…”