Optical parameters of graphene/MoS2 van der Waals heterostructure investigated by spectroscopic ellipsometry

Van der Waals (vdW) heterostructures integrated by stacking of different two-dimensional (2D) materials have demonstrated their great potential for various applications, especially for the next-generation optoelectronic devices due to their new physics and exceptional properties in the past years. However, the specific influence of interlayer coupling on electronic structure and photoelectric properties is of great significance but rarely studied with an experimental and effective method. Here we firstly analyze the optical parameters of graphene/MoS2 vdW heterostructure by a fast and non-destructive characterization technique, spectroscopic ellipsometry (SE). The Lorentz oscillators modeling dispersion relations and effective medium approximation layer fit well with the SE measured data. The yielded refractive index and extinction coefficient of graphene/MoS2 vdW heterostructure were confirmed and compared to investigate their optical properties and interface interactions. These results provide a fundamental understanding on the optical parameters and interlayer coupling of graphene/MoS2 vdW heterostructure, which could promote the further research of various vdW heterostructures and future development for use in optoelectronics.