Consistent refractive index parameters for ultrathin SiO2 films

Refined values are obtained in the present study for the refractive index parameter (n) for ultrathin SiO2 films (less than 8 nm in film thickness, Lox) and summarized as n=2.139−8.991×10−2×Lox+1.872×10−3×Lox2. This formula was obtained starting from variable angle of incidence ellipsometry data on ultrathin SiO2 films, and a previously derived refractive index parameter formula that was based on independently measured thickness’ using Fowler–Nordheim electron tunneling measurements. The new n values are useful for extracting more accurate ultrathin SiO2 film thicknesses from ellipsometry measurements.