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Center for Astrophysics Research and Technologies Seminar Series Information

 

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Infrared Chameleon: Graphene, Surrounding Materials, & the Primacy of their Interaction on Photodetection

Thursday December 8, 2016
11:00 am


 Presenter:  Dr. Thomas Beechem, Sandia Natl. Labs
 Series:  OSE Seminars
 Abstract:  Graphene photodetectors are being pursued for applications spanning from the UV to THZ owing to the material's unique characteristics-large mobility, lack of bandgap, and malleable optical conductivity-unavailable in traditional paradigms. Within the IR, these material responses advantageously converge providing the promise of ultrafast hyperspectral detection. The same two-dimensional nature imbuing graphene this promise also inhibits its use, however. Sensitivity is inherently damped by the challenges of creating and collecting photogenerated charge in a 2D-material interfaced to a 3D-world. Practical realization of graphene-enabled hyperspectral detection therefore depends upon not only the material itself but also its interfacing with the materials surrounding it. To illustrate, the hyperspectral characteristics of nanonantenna enhanced graphene detectors are assessed showing the prime role that adjacent materials have on both light absorption and charge collection.

First, the magnitude and gate-tunable wavelength range of graphene absorption is found to be highly dependent upon the dielectrics ostensibly used as the gate oxide. Subsequently, non-uniform resistivity of the graphene-and thus collection of photogenerated charge-is shown to be implicitly linked to the morphological irregularities of the surface upon which it was synthesized. Taken together, these case studies highlight both the potential of graphene-based hyperspectral detection and the remaining obstacles hindering its adoption.
 Location:  Room 103, Center for High Tech Materials

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