John A. Woollam, the 2017 ICMCTF laureate, is recognized for "seminal contributions to the development and application of ellipsometry as a primary technique for determining thin-film optical properties."
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John Woollam received a B.A. degree in
physics from Kenyon College in Gambier, Ohio (1961), and
M.S. (1963), and an Ph.D. (1967) degrees in Solid State
Physics from Michigan State University, East Lansing, MI. In
1978, he received an M.S. in Electrical Engineering from
Case Western Reserve University, Cleveland, OH.
John is a Fellow of the American Physical Society (APS) and the American Vacuum Society (AVS) as well as having been honored as a fellow of the National Academy of Inventors (NAI) and the National Research Council. He was also honored with the American Physical Society Prize for "Industrial Application of Physics" in 2012.
Upon receiving his Ph.D., John worked at the NASA Lewis Research Center in the Cryophysics Section from 1967-1979, after which he became Professor of Electrical Engineering at the University of Nebraska. John was named George Holmes University Professor at the University of Nebraska in 1986.
Since 1964, John has co-authored more than 430 journal articles, written 26 invited review articles, and received 59 Patents.
His research at NASA involved fundamental electronic and thermal studies of carbon, graphite, and carbon fibers. He used layered-structure materials as hosts for intercalation compounds studied by electron and thermal transport. Much of this work involved high magnetic fields and temperatures from near absolute zero to 700 K using facilities at both NASA Lewis Research Center and the Francis Bitter National Magnet Laboratory at the Massachusetts Institute of Technology (MIT). While at NASA John worked closely with materials scientists and engineers in government, industry, and university laboratories to produce and characterize high-temperature (when this meant 21 K), high-current superconductors for high-field magnets.
At the University of Nebraska John inherited a null-elllipsometry laboratory from Professor Nicholas Bashara. Null ellipsometry was far too slow for viable use in materials science and engineering, so he hired engineering students and post-docs to help automate the instrumentation. This led to the ability to obtain significant grant funding at the University of Nebraska, Lincoln (UNL), starting in the 1980s, to characterize compound semiconductors, as well as dielectric films needed for high-speed optical and electronic devices, for example for satellite-to-satellite communication, or for protective coatings used in low-earth-orbit. Most of John’s scientific work was in collaboration with numerous undergraduates and more than 30 graduate students.
In the late 1980s, science colleagues showed interest in having the automated ellipsometers developed at UNL. At the same time students were having a difficult time finding jobs, so John started the J.A. Woollam, Co, Inc., now a worldwide leader in spectroscopic ellipsometry.
John continues to teach at UNL, collaborate with colleagues, and work with R&D teams to develop and manufacture wide-spectral-range ellipsometers used in an ever expanding range of industrial and scientific applications.
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History and Basics of Ellipsometry with Examples
Interesting changes in polarization state of light upon oblique angle reflectance from (or transmission through) flat smooth materials were first explored by Paul Drude in Berlin, Germany, in the late 1800s. One of the first practical applications was to regulate sugar sales by measuring polarization rotation in solutions. The first U.S. Ellipsometry Conference was held at The National Bureau of Standards in 1963. Since then, the field has advanced rapidly in both basic knowledge and applications. Advancement of personal computers in the 1980s and 90s led to dramatic improvement in speed and utility of ellipsometry. This led to explosive increases in users. The first International Conference on Spectroscopic Ellipsometry was held in Paris in 1983, and conferences are generally held every three years.
The basic concept of ellipsometry is that a beam of electromagnetic radiation of known polarization state is directed at an oblique angle to a material of interest and the reflected (or transmitted) beam polarization state determined. This can be done with a range of angles of incidence and wavelengths. Optical modeling and regression allows one to infer numerous properties of the material. Examples are surface roughness, film thickness, index of refraction (sometimes graded), extinction coefficient, atomic ratios in alloys, crystallinity, etc. Ellipsometers are also used for optical critical-dimensional (OCD) metrology of integrated circuits. Other applications include microelectronics, organic materials, solid-state lasers, display technology, optical coatings, hard coatings, energy efficiency, solar energy, solid lubricants and lighting. In basic science, optical transitions are used to determine unknown parameters in energy bands of solids, crystallinity, and surface and interface chemistry with sub-nanometer dimensional sensitivity. Finally, new developments involving different spectral ranges, in situ, in-line technology, and combinations of ellipsometry with other techniques will be discussed.