Effects of disorder on the optical properties of CVD grown polycrystalline graphene

Abstract

We explore the effects of crystallite size (L(a)) on the linear and non-linear optical properties of chemical vapor deposition grown polycrystalline graphene. The π-plasmon resonance present at ∼4.75 eV (∼260 nm) in the optical absorption spectrum of graphene follows the empirical relationship λ(π) = 250.5 nm + 89.5 nm(2)/L(a), where λ(π) represents the π-plasmon wavelength. Furthermore, our Z-scan studies reveal that the crystallite size significantly changes the saturation intensity in CVD grown graphene. Notably, in comparison to epitaxial graphene layers grown on SiC wafers which exhibit a photogenerated carrier lifetime of few picoseconds, we find that the photogenerated carriers in our CVD grown graphene can exhibit lifetimes as long as nanoseconds.

Nonlinear optical absorption and asymmetric charge carrier conduction in chemical vapor deposited single-layer graphene

“…The measured saturation intensity is low when compared to the reported values in various spectral ranges, especially at visible range [47][48][49][50][51][52][53][54]. However, it is comparable with the theoretical value [55].…”

“…The highest reported values is close to 4 GW cm −2 for single layer graphene [47]. Podila et al have reported that graphene films having less disorder will have the highest saturation intensity owing to its longer recombination time [48]. They reported the lowest value for graphene film having the maximum disorder.…”

Nonlinear optical properties of nitrogen-doped bilayer graphene

“…1 suggesting the role of defects in the NLO properties of doped graphene. Previously NLO studies done on polycrystalline graphene showed that saturation depth increases as a function of the number of graphene layers due to the increase in disorder in the graphene lattice [4]. In the present case too, the highest saturation depths are observed with N3 and N1 which contain maximum number of defects due to the lattice disruption by nongraphitic dopants.…”

Effects of Substitutional Doping on the Nonlinear Optical Properties of Single-walled Carbon Nanotubes

“…Increase in defects with substitutional doping is further confirmed by the decrease in I S values ( Fig. 2(b)) in the ultrafast regime [6]. Another factor affecting NLO properties in doped nanotubes could be the changes in the metallicity of the nanotubes with B-doping.…”