NSTRUMENTATION

NSTRUMENTATION

The IR-VASE from J. A. Woollam Co. (Lincoln, NE) is an infrared variable-angle spectroscopic ellipsometer that offers nondestructive characterization of thin films and bulk materials over an unusually wide spectral range. The instrument, introduced in January 1998, derives its wide-spectral-range capabilities from a rotating compensator, which, though challenging to develop, offers superior measurement performance. The IR-VASE provides an unambiguous measurement of delta data from 0 to 360 and measures all wavelengths simultaneously. It can measure both n and k directly for materials from 2 to 33 µm without extrapolating data outside the measured range, which makes it ideal for measuring optical coatings, semiconductors, polymer films, and metals. For implanted layers and epitaxial films, it can characterize the free-carrier profiles varying with depth in silicon.