Intriguing Absorption Band Behavior of IR Reflectance Spectra of Silicon Dioxide on Silicon

Abstract

Infrared reflectance spectra of a thermally grown 30-nm SiO₂ film on a Si wafer were measured as a function of incident angle and polarization. Spectra measured with s-polarized light resemble the published extinction coefficient for SiO₂. The p-polarized spectra show significant distortions at all incident angles. Bands change in frequency and intensity and can even invert as the incident angle increases beyond the Brewster angle of the Si substrate. Spectral simulations using the classical electromagnetic equations reproduce these distortions.