1998 Annual Report: Materials Science and Engineering

hands-on approach in the freshman design course (EPD 160) has shown success in retaining freshman in engineering. Noting this success, Professor Eric Hellstrom introduced a more hands-on approach to his MS&E 250 class last spring with encouraging results. Hellstrom gives students boom boxes to disassemble and study. Previously, MS&E 250 involved bringing in MS&E faculty speakers to talk generally about their field of expertise. Now, the speakers use the components of the boom box as the context for their lectures -- explaining to the students in materials science terms what they are looking at--semiconductors, integrated circuitry, crystal growth, packaging, etc. Students are also introduced to scanning electronic microscopy as they examine the microstructure of the various boom box components with the microscope. MS&E 250 covers a broad range of topics and is designed to get students excited about materials science. "We've only used this format one semester and had a much higher retention rate than in the past," Hellstrom says. "In previous years, retention was about 25 percent. Of the 18 freshman without declared majors who took MS&E 250 this spring, 14 plan to continue in materials science. That's good news."

Researchers at the Synchrotron Radiation Center (SRC) developed a source of soft X-rays that could spawn a new research area in the damage and repair of cell nuclei. As reported in the April 24 issue of the journal Science, geneticists used the SRC's soft X-ray source to irradiate one-micron-wide stripes of cell nuclei through a mask. "Typically a half dozen stripes fit into a nucleus," says Professor Max Lagally. "The repair of DNA damage can now be studied with one-micron lateral resolution."

Radiation causes damage to DNA double-strands which the nucleus is sometimes able to repair. To observe sites within damaged cells, Lagally, SRC researcher Jim MacKay, and Professors Mike Gould (oncology,) Paul deLuca (medical physics), Rockwell Mackie (medical physics) and Ben Nelms used soft X-rays and microfabricated irradiation masks to induce DNA damage in discrete subnuclear regions of irradiated cells.

Medical School Assistant Professor of Medical Genetics John Petrini, working with researchers Nelms and Rick Maser, used the technique to show special repair proteins at work, moving immediately from their home bases to remote gene damage sites. The new observation method opens up a wide range of possible experiments in cell damage and repair.

A team of college faculty is working to create new classes of substrates for the growth of high-quality semiconductor thin films. The group includes Professors Thomas Kuech, chemical engineering, Max Lagally, physics and materials science and engineering (MS&E), Richard Matyi (MS&E), Susan Babcock (MS&E), Roxann Engelstad, mechanical engineering (ME) and Edward Lovell (ME). Novel substrates on which defect-free materials can be grown are crucial to a variety of new technologies, including the manufacture of high-quality GaN-based materials for laser and light-emitting diode applications and high-power, high-temperature electronics. The group is researching two parallel, complementary approaches. The first uses a low viscosity boro-silicate glass layer to mechanically decouple a continuous template layer and the growing film from a necessary, but ordinarily (i.e., in conventional substrates) constraining handle wafer.

In the second approach, the growing material is seeded on poorer quality conventional material to establish the single crystal, and then laterally grown over glass, which again removes the mechanical constraints that normally lead to defect incorporation in the film. The group is funded as a Multidisciplinary Research Program of the University Research Initiative (MURI) through the Office of Naval Research.

276 Materials Science and Engineering Building
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Tel: 608/262-3732
Fax: 608/262-8353
E-mail: hellstrom@engr.wisc.edu
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