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

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.