University of Nebraska-Lincoln College of EngineeringOnline: Spring 2012
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  John Woolam left, Electrical Engineering graduate student Brian Rodenhausen works with Biological Systems Engineering graduate student Tadas Kasputis on biomedical thin films applications using ellipsometry.  

 

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Ellipsometry measures thin films applied as coatings to the surfaces of materials. In electronics these thin coatings control how a material can store data, display images on screens, or determine how well a solar cell converts light into energy. Ellipsometry plays an important role in measuring coatings for these important, everyday applications and more. It’s worth wondering: without ellipsometry, would we enjoy the proliferation of electronic technology we have today? How did ellipsometry become a renowned area of strength at the University of Nebraska? And what are its possibilities for the future?


Past | Present | Future

FUTURE
Schubert photoAs Bashara passed the Nebraska ellipsometry torch to Woollam, in turn Mathias Schubert carries it to enlighten new frontiers in advancing the research in optics and beyond.

Schubert, professor of electrical engineering, was an undergraduate at Universitat Leipzig in Germany—another great center of ellipsometry—when he first visited Lincoln. It was 1993 when he was first hosted by Woollam’s research group; Schubert had been sent to Nebraska to “learn how to do ellipsometry” with equipment purchased by the department where he studied.
He spent his time focused on semi-conductor applications, and “before my return flight, John took me to O Street for a beer and started talking about possibilities in characterizing anisotropic materials—a wild idea,” Schubert recalled. “John said ‘work on it,’ and I did … I came back to Nebraska each year to work on another application and solve another problem.”

When Woollam scaled back from UNL, Schubert was hired as an associate professor: an ideal opportunity to carry on the university’s ellipsometry operations. “I brought with me a 40-foot container with equipment including prototypes that blended with UNL’s work,” Schubert said. “I also brought three students and one post-doctoral research associate, and soon we were collaborating throughout the department and campus.”

Schubert’s team quickly integrated with EE colleagues and beyond, including Shannon Bartelt-Hunt in Civil Engineering, Angela Pannier in Biological Systems Engineering, Patrick Dussault and Rebecca Lai in Chemistry, and Stephen Ducharme in Physics.

 

Schubert is recognized for his cutting-edge work in applying existing methods in new research. His Optical Hall effect, discovered using instrumentation built at UNL with support from the National Science Foundation, applies generalized ellipsometry to materials with free electrons subjected to external magnetic fields—something early experts predicted but couldn’t prove.

His work relates to analyzing electrical conductivity in multiple layered structures, and helps with characterizing novel materials for modern electronics devices, with structures and materials that are naturally best-suited for the application. It earned Schubert designation as a Fellow of the American Physical Society (APS) and prompts strong international collaboration—with frequent visitors to Leipzig and Lincoln among a core group from France, Sweden, Africa, Portugal, Spain and Great Britain. These peers welcome his Nebraska students to join in an elite research community.

UNL also sends a strong contingent to meetings of the American Vacuum Society (AVS) and is part of the programmatic leadership, Schubert said, adding that many research partners come to AVS “because we are there.”

With funding through the Nebraska Experimental Program to Stimulate Competitive Research (EPSCoR), Schubert is co-directing with Dussault the newly formed UNL Center for Nanohybrid Functional Materials (CNFM), which combines 17 principal investigators throughout the state. Ellipsometry is at the heart of this multi-faceted endeavor, helping to characterize materials for a range of uses, and Schubert envisions a lab with a large footprint, now taking shape in Scott Engineering Center.

“One focus of CNFM is organic materials,” Schubert explained. This gathering of partner researchers opens new areas of work and funding: “Suddenly we are talking about sensing and detecting how cancer may develop, how diseases spread, how aging progresses—targeting current and future properties of materials highly relevant for life sciences.” He cites work underway with established companies including Procter & Gamble, Osram, Emcore Corp., and Nvisage Technologies.

Opportunities to work with companies that could grow at Nebraska Innovation Campus excite Schubert and his team. “It’s a fantastic time for research [and ellipsometry] at UNL—it’s becoming stronger and with much more impact.”

 
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