light source on the surface of the sample is 2 mm. Computercontrolled slit widths adjust the bandwidth to insure adequate
spectral resolution of optical features in the data. These include
closely spaced interference oscillations, which arise in very thick
films. A photomultiplier tube is utilized for signal detection in the
ultraviolet. A stacked Si/InGaAs photodiode detector is used for
longer wavelengths. Ellipsometric measurements were conducted
using light incident at angles of 65–751relative to normal on the
front surface of the sample, the back of which was roughened
with coarse polishing paper. The instrument measures the ellipsometric parametersCandD, which are defined by [