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        COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER
                   School of Computational Sciences
                           (CSI 898-Sec 001)
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 Interface structure and device properties of SrTiO3 on Si (001)

                   Kristopher E. Andersen

          Center for Computational Materials Science
          Naval Research Laboratory, Washington, DC

The need to replace SiO2 as the gate dielectric in Si based
microelectronic devices has lead to the investigation of many
alternative oxides, of which, one of the more promising is SrTiO3
(STO). Since the lattice mismatch between STO and the Si (001) surface
is small, it is possible to grow STO on Si using a nontrivial
molecular beam epitaxy process pioneered by McKee et al. However, (i)
achieving well-order growth is difficult, (ii) the interface structure
is poorly understood, and (iii) the conduction band offset of the
heterostructure has been found to be too small (< 0.2 eV) for device
applications. Using first-principles density functional theory
calculations of the energetics of numerous proposed interfaces, we
find the favored structure is one that has not been previously
considered and is consistent with several experimental probes.
Furthermore, the electric polarization of the STO thin film plays an
important role, and our calculations suggest that doping the interface
with Na, K, Al, or Sc may improve the device properties of the
heterostructure.

                          September 25, 4:30 pm
                   Room 301, Research I, Fairfax Campus

Refreshments will be served at 4:15 PM.
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Find the schedule at http://www.cmasc.gmu.edu/seminar/schedule.html
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