Optical characterization of low-index transparent thin films on transparent substrates by spectroscopic ellipsometry

The potential usefulness and limitations of spectroscopic ellipsometry in the optical characterization of low index transparent thin films on transparent glass substrates of only slightly lower index are demonstrated by Monte Carlo simulation. Whereas the film thickness and refractive index may be accurately determined to +/-3 A and +/-0.0015, respectively, the extinction coefficient cannot be obtained accurately. Results are independent of the angle of incidence and film thickness.