Temperature-Dependent Optical Properties of Graphene on Si and SiO2/Si Substrates

Systematic investigations are performed to understand the temperature-dependent optical properties of graphene on Si and SiO2/Si substrates by using a variable angle spectroscopic ellipsometry. The constants have revealed changes with substrate temperature. While refractive index (n) monolayer exhibited clear anomalous dispersions in visible near-infrared region (400–1200 nm), modification is moderate for substrate. Two sheets shown pronounced absorption ultraviolet peak position related Van Hove singularity density states. By increasing temperature from 300 K 500 K, Si, n value gradually increased while k decreased. However, [n, k] unpredictable wave variations. In wavelength range 400–1200 nm, an experiential formula like-Sellmeier equation found well suited describing substrates.