THOMAS E. FURTAK

Summary of Research Interests

Condensed matter physics; optical properties of surfaces and interfaces; nonlinear optics; polymers and self-assembled systems.

Many advanced technologies, such as direct energy production through solar cells, chemical processing by catalysis, and nanofabrication using self-assembled systems are currently limited by the properties and behavior of interfaces. Many of these boundaries involve thin films or "buried" surfaces. It's possible to gather information about chemical and molecular identities, as well as material geometry and bonding configurations at these very thin regions by exploiting special techniques involving light.

For example, the polarization state of light is modified by the dielectric discontinuity at an interface. The dielectric function is closely connected to the energy states of the electrons in the materials. These, in turn, depend upon all kinds of things...stress, voids, impurities, to mention a few. Using an ellipsometer we can measure this modification to the polarization state of the light with very high precision. It's possible to detect the influence of a single monomolecular layer. The experiment is performed with monochromatic light whose wavelength can be varied. We are using spectroscopic ellipsometry to study promising thin-film photovoltaic materials, such as copper-indium-gallium-diselenide. We have also developed a new version of the instrument that we call the parallel detecting spectroscopic ellipsometer (PDSE). The new device fits inside of a processing chamber and provides information about the properties of a growing film in real time.

The Surface Optical Spectroscopy Group is also working on a couple of nonlinear optical techniques. They both involve combining two photons in the sample to produce a single outgoing photon. Second harmonic generation (SHG) and sum-frequency generation (SFG) share a common sensitivity for interfaces through the symmetry properties of the two-photon conversion. With SFG one of the two photon sources is tunable in the infrared. This makes it possible for us to extract a vibrational fingerprint from molecules at the interface, even if the interface is under water or at the boundary of a material and its oxide. We are using these techniques to examine self-assembled organic monolayers that are used for liquid crystal alignment, biocompatible coatings, high-resolution lithography, and structured lubrication layers. Other projects in our laboratory involve the use of elastic and inelastic light scattering (Raman spectroscopy).

It's all very interesting work with strong connections to basic science and many productive applications.

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 Last Modified: 8/27/2006