Optical properties of large-area polycrystalline chemical vapor deposited graphene by spectroscopic ellipsometry

Abstract

Spectroscopic ellipsometry was used to characterize the complex refractive index of chemical vapor deposition (CVD) graphene grown on copper foils and transferred to glass substrates. Two ellipsometers, with respective wavelength ranges extending into the ultraviolet and infrared (IR), have been used to characterize the CVD graphene optical functions. The optical absorption follows the same relation to the fine structure constant previously observed in the IR region, and displays the exciton-dominated absorption peak at ∼4.5 eV. The optical functions of CVD graphene show some differences when compared to published values for exfoliated graphene.

Determination of a refractive index and an extinction coefficient of standard production of CVD-graphene

“…7 and ESI †). Comparing these results with the others previously reported, 16,18,28 it is evident that although a better agreement can be achieved in the near UV region, it fails in the visible range. Therefore, a variable graphene thickness would not be the reason for the inappropriate n, k values obtained after data analyses using the sample structure proposed in Fig.…”

Visible to vacuum ultraviolet dielectric functions of epitaxial graphene on 3C and 4H SiC polytypes determined by spectroscopic ellipsometry

“…The e 2 spectra are dominated by the well known CP transition. [13][14][15] Comparing the CP peak energies 30 of graphene (4.53 eV) and graphite (4.37 eV) in Fig. 3 reveals that 4H-Si (4.51 eV) is closest to graphene.…”

“…12 This singularity can be associated with the characteristic critical-point (CP) feature observed in dielectric function spectra of exfoliated graphene 13,14 and graphene grown by chemical vapor deposition for photon energies around 4.5 eV. 15 In this work, we report dielectric function spectra for epitaxial graphene layers grown by thermal sublimation on 3C, 4H silicon-face, and 4H carbon-face silicon carbide from the visible light region to the ultra-violet (3.5-9.5 eV). The dielectric function spectra are obtained from spectroscopic ellipsometry measurements and subsequent model dielectric function (MDF) analysis.…”

Investigation of the optical properties of MoS2 thin films using spectroscopic ellipsometry

“…16 It is frequently used in industry for film characterization and in in-situ thickness monitoring because it is fast, cheap, and non-destructive. In recent years, SE has been employed to investigate the optical constants of graphene; [17][18][19][20] however, to date, SE characterization of 2D layered TMDs, such as MoS 2 , has rarely been reported.…”