Current Research

    We have focused our research in recent years on thin films. This involves film preparation, and characterization by numerous experimental techniques. These include atomic force microscopy, spectrophotometry, optical interference microscopy. Our specialty however is spectroscopic ellipsometry. We cover the spectral range with existing ellipsometers from 0.023eV to 6.6eV. Ellipsometers measure optical constants, thin film layer thickness, alloy concentrations, surface roughness, sample temperature, and can be used on multilayered condensed matter samples with nanometer scale dimensions.
Our most recent research is on biomaterials at interfaces, especially protein attachment to various surfaces. For these studies we use in situ and ex situ spectroscopic ellipsometry (including both visible and infrared spectral ranges), contact wetting angle measurements, atomic force microscopy, interference microscopy and visible and infrared spectrophotometry. Studied are the kinetics of attachment, and surface orientations of various molecules and combinations of molecules at molecular surfaces and in interfaces of individual molecular layers. Molecular layers as thin as a single molecule with dimensional scales of a few nanometers are studied and characterized.
We are funded by the National Aeronautics and Space Administration (NASA) working on thin films for spacecraft chemical, mechanical, and thermal protection from the space environment of atomic oxygen, ultraviolet radiation, and particulate and chemical contamination from other activities in space. We are also funded by Boeing Aircraft Corporation for similar purposes.
Students in our laboratories work on degrees in Electrical Engineering (MS and PhD), Physics (PhD), and Chemical and Materials Engineering (PhD), and Biomedical Engineering (PhD).

Recent Key Publications

J.A.Woollam , J.N. Hilfiker, C.L.Bugay, R.A.Synowicki, T.E.Tiwald, and D.W. Thompson, “Spectroscopic Ellipsometry From the Vacuum Ultraviolet to the Far Infrared”, in Characterization and Metrology for ULSI Technology, AIP CP550, 511-518 (2001). Invited.

B. Johs, J.Hale, N.J. Ianno, C.M.Herzinger, T.Tiwald, and J.A.Woollam, “Recent Devleopmentes in Spectroscopic Ellipsometry for in situ Applications “, SPIE 4449, 41 (2001). Invited.

J.Hilfiker, J.S. Hale, B.D.Johs, T.E.Tiwald, R.A.Synowicki, C.L.Bungay, and J.A.Woollam, “Spectroscopic ellipsometry in Optical Coatings manufacturing”, Proceedings of the Society of Vacuum Coaters, (2001). Invited.

M. Schubert, A. Kasic, S. Einfeldt, D.Hommel, U. Kohler, D.J.As, J. Off, B. Huhn, F. Scholz, and J.A.Woollam, “Infrared Ellipsometry – a Novel Tool for Characterization of Group-III Nitride Heterostructures for Opto-electonic Device Applications”, Phys. Stat. Sol. (b) 228, 437 (2001).

S. Zangooie, D.W. Thompson, J.A. Woollam and M. Schubert, “Infrared Response of Multiple Component free-carrier plasma in heavily doped p-type GaAs”, Appl. Phys. Lett. 78 (5), 1-3 January (2001).

S. Zangooie and J.A. Woollam, “Ellipsometric Characterization of Thin Porous GaAs Layers Formed in HF Solutions”, J. Mat. Sci. Letts. 19, 2171 (2001).

L. Yan, X. Gao, C. Bungay and J.A. Woollam, “Study of Surface Chemical Changes and Erosion Rates for CV-1144-O Silicone under ECR Oxygen Plasma Exposure”, J. Vac. Sci. Technol. A19, 447 (2001).

E. Franke, M. Schubert, C.L. Trimble, M.J. DeVries and J.A. Woollam, “Optical Properties of Amorphous and Polycrystalline Tantalum Oxide Thin Films Measured by Spectroscopic Ellipsometry from 0.03 to 8.5 eV”, Thin Solid Films 338, 283 (2001).

S. Zangooie, M. Schubert, D.W.Thompsonk and J.A.Woollam, “Infrared Response of Multiple-component Free-carrier Plasma in Heavily doped p-type GaAs”, Applied Phys. Letts. 78, 1 (2001).

S. Zangooie, M. Schubert, C. Trimble, D. Thompson and J.A. Woollam, “Infrared Ellipsometry Characterization of Porous Silicon Bragg Reflectors”, Applied Optics 40 (6), 1-7 (2001).

Recent Graduates and Current Affiliations

Corey Bungay, M.S. 2001, with the J.A.Woollam Co., Inc. Lincoln, NE
Thesis: “Materials in the Space Environment”
Thomas E. Tiwald, PhD. 1999, with J.A.Woollam Co., Inc., Lincoln NE
Dissertation: “Measurement of Free Carriers in Silicon and Silicon Carbide using Infrared Ellipsometry.”
Xiang Gao, PhD. 1999, now with Emcore Corporation, NJ
Dissertation: “Magneto-Optic and Dielectric Properties of Magneto-optic Materials”
Michael J. DeVries, M.S. 1999. Now with IBM Corporation, VT
Thesis: “Ellipsometric Investigation of Electrochromic Materials”