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Department News
Imaging 'Invisible' Dopant Atoms
Nanometer-scale semiconductors that contain a few intentionally added impurity atoms can provide new opportunities for controlling electronic properties. However, since the physics of these materials depends strongly on the exact arrangement of the impurities, or dopants, inside the structure, and many impurities of interest cannot be observed with currently available imaging techniques, new methods are needed to determine their location. Mkhoyan group in collaboration with David Norris's group from ETH Zurich combined electron energy loss spectroscopy with annular dark-field scanning transmission electron microscopy (ADF-STEM) to image individual Mn impurities inside ZnSe nanocrystals. Thus, a general path is demonstrated for atomic-scale imaging and identification of individual dopants in a variety of semiconductor nanostructures.
Michael Tsapatsis elected AAAS Fellow
Michael Tsapatsis was elected Fellow of the American Association for the Advancement of Science (AAAS) by the AAAS Council. Each year the Council elects members whose "efforts on behalf of the advancement of science or its applications are scientifically or socially distinguished."
Sai Madhukar Reddy wins Best Poster Award
Sai Madhukar Reddy, a CEMS graduate student working with Beth Stadler in Electrical and Computer Engineering, won a Best Poster Award at the Magnetism and Magnetic Materials (MMM) conference in Scottsdale, AZ. Madhukar's poster was entitled "Towards Epitaxial Fe1-xGax / GaAs Structures via Electrochemistry for Spintronics Applications" and describes his work demonstrating an ability to electrochemically deposit epitaxial Fe-Ga thin films on GaAs substrates. The work also enables one to tailor the film texture to suit the application in hand, likely in the areas of semiconductor spintronics and MEMS/NEMS devices.
CEMS group reports breakthrough on zeolite films
A CEMS team described the synthesis of suspensions containing zeolite nanosheets (precisely structured porous layers, few atoms thick and thousand atoms wide). Due to the molecular sized pores crossing the film thickness, the nanosheets can act as selective flakes at the molecular level. High performance membranes were synthesized by simply packing these selective flakes. The paper was published on the October 7 issue of Science (K Varoon et al, Science, 2011, 334, 72 (DOI: 10.1126/science.1208891)). A commentary can be found at http://www.rsc.org/chemistryworld/News/2011/October/06101105.asp
20 Recent CEMS Graduates and Postdocs Start as Faculty Around the World from MIT to University of Science and Technology in China
One of CEMS missions is to educate the next generation of chemical engineering and materials science faculty. Towards this goal, 20 recent graduate students and postdocs of CEMS faculty started their careers as professors at universities across the United States and the globe. Eight of the 20 will be teaching in Brazil, China, Japan, Korea, Taiwan and the United Arab Emirates. Click on "Read More" for a complete list. We wish all of them good luck in their new positions.
High-Throughput Zeolite Membranes
In an invited Perspective (Science, 334, p.767 (2011)), Michael Tsapatsis discusses an emerging new methodology to fabricate ultrathin (few nanometer thick) molecular sieve membranes. This technology appears now feasible due to several notable developments demonstrated by his research team and collaborators: control of preferential orientation (Science, 300, p. 456 (2003)) , elimination of grain boundary defects (Science, 325, p. 590 (2009)) and synthesis of nanosheet seed crystals (Science, 333, p. 72 (2011)). Commercialization of this technology could lead to significant energy savings in the chemical process industry.
