Nicholas James Smith

Low energy ion scattering (LEIS). A practical introduction to its theory, instrumentation, and applications

Low energy ion scattering (LEIS) probes the elemental composition of the outermost atomic layer of a material and provides static depth profiles of the outer ca. 10 nm of surfaces. Its extreme surface sensitivity and quantitative nature make it a powerful tool for studying the relationships between surface chemistry and surface related phenomena such as wetting, adhesion, contamination, and thin film growth. The high depth resolution obtained in LEIS in its static and sputter depth profile modes are useful for studying the layer structures of thin films. LEIS instrumentation has improved significantly in recent years, showing dramatic increases in its sensitivity and further expanding its potential applications. In this article, we provide a practical introduction to the technique, including a discussion of the basic theory of LEIS, LEIS spectra, LEIS instrumentation, and LEIS applications, including catalysts, solid oxide fuel cells (SOFCs), and thin films in integrated circuits.

Eagle XG® glass, optical constants from 230 to 1690 nm (0.73 - 5.39 eV) by spectroscopic ellipsometry

Eagle XG® glass is widely used in the manufacture of electronic displays. Spectroscopic ellipsometry and transmission data for this material were obtained from 193 to 1690 nm. The optical constants of the material were then modeled from 230 to 1690 nm. The data were initially fit with a basis spline (B-spline), and these results were used as the starting point for either a two-Gaussian oscillator model or a Tauc-Lorentz (T-L) + Gaussian oscillator model. Both models gave good fits, with unweighted mean squared error values of ca. 1.1. Samples were provided by Corning Incorporated directly from their production facility.

Optical constants of SiO2 from 196 to 1688 nm (0.735–6.33 eV) from 20, 40, and 60 nm films of reactively sputtered SiO2 on Eagle XG® glass by spectroscopic ellipsometry

Three thicknesses of reactively sputtered SiO2, nominally 20, 40, and 60 nm, deposited on Corning Eagle XG® (EXG), an important display glass, were analyzed by spectroscopic ellipsometry. Reflection ellipsometry data from the samples were analyzed from 196 to 1688 nm at angles of 55°–60°, inclusive, in 1° increments. These angles were chosen because they bracket the Brewster angles of both EXG glass and SiO2. The backsides of the samples were roughened by sand blasting to suppress backside reflections from the substrates. A total of nine datasets were collected from nine different samples (three for each nominal thickness of SiO2), each at six different angles of incidence (54 spectra). The optical constants for each thickness of SiO2 was determined, as well as a set of constants for all the films (the material in general) via a multisample analysis (MSA). The optical constants of the SiO2 films were modeled using two poles with transparency assumed over the entire spectral range (a Sellmeier model). A Br...