3D and 2D Nano-fabrication with Elastomeric Phase Masks
Jul 30, 2014
from 03:00 PM to 04:30 PM
|Where||Engr. IV Bldg., Maxwell Room 57-124|
|Contact Name||Prof. Aydogan Ozcan|
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This presentation covers Dr. Shir’s PhD work on optical techniques and soft imprint lithography for making 2D and 3D nanostructures. The approach, which we refer to as proximity field nanopatterning (PnP) or phase mask lithogrphy, uses conformable, elastomeric phase masks to pattern thick layers of transparent, photosensitive materials in a conformal contact mode geometry. The first part of the presentation focuses on exploiting the patterning capability of phase mask lithography in the following approaches: (1) Combining PnP with soft imprint techniques to form complex structures with large dimensional flexibility. (2) Dual exposures, two-photon phase mask technique for producing woodpile polymer structures studies of its optical property both experimentally and through simulations. (3) Utilizing quasi-periodic phase masks to form unusual classes of three dimensional (3D) nanostructures. The resulting nanostructures show interesting features, including quasicrystalline layouts in planes parallel to the sample surfaces, with completely aperiodic variations through their depths, consistent with the optics. (4) Using soft imprint technique to generate light trapping structures for improving the energy conversion efficiency of thin film Si solar cells. Simulations and spectroscopic measurements of transmission, reflection, and absorption reveal insights for designed light trapping structures. Photovoltaic performance measurements on a 6 um Si solar cell showed energy conversion efficiency improvements over 80 % compared to bare Si. Spectral-resolved efficiency measurements reveal results consistent with simulations.
Daniel Shir was born in Durham, North Carolina in 1983. He received his B.S. with distinction in Materials Science and Engineering from the Pennsylvania State University in 2005. After graduation, he joined the Ph.D. program in Department of Materials Science and Engineering at University of Illinois under the guidance of Prof. John A. Rogers. During his Ph.D. study, he published 10 peer-review journal articles and 1 book chapters. Topics of his work include soft lithography, phase mask lithography, 3D photonic crystals, and Si photovoltaics. On completion of his degree, he worked as a process development engineer at join Intel Corp. from 2010 to 2014.