Signal Level Regulation and Dark Current Composition for Wavelength Scanning Ellipsometer
Original Publication Date: 1978-Jul-01
Included in the Prior Art Database: 2005-Feb-21
Spectroscopic ellipsometry is a recently developed tool for measuring optical properties of bulk and thin-film materials. Precision of 2 parts in 100,000 has been demonstrated. Weak structures in the spectral curves of the complex dielectric function may be enhanced by triple differentiation with respect to wavelength (or energy). (See D. E. Aspnes, Opt. Commun. 8, 222-225 (1973).) It is usually necessary to smooth the experimental data prior to differentiation. This removes the random part of the measurement error. It is important to avoid introducing systematic error into the measurement.