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Research & Reviews: Journal of Material Sciences | ISSN: 2321-6212 | Volulme 6
November 07-08, 2018 | Atlanta, USA
Materials Science and Engineering
15
th
International Conference and Exhibition on
Applied Crystallography
3
rd
International Conference on
&
Topotactic anion exchange in epitaxial films: Synthesis advantages and characterization challenges
Statement of the Problem:
Despite direct epitaxial deposition/facet-growth of innumerable materials in lab experiments, new
lattice-matched buffer (interdiffusion-blocking) layers are desperately needed by the microelectronics industries. There is a need
for "substrate agnostic" buffer layer(s) to template epitaxial growth on Si, GaN, Ni and others. Epitaxial templates, particularly
ultra-thin oxide layers, have been demonstrated to be excellent epitaxial buffer layers, but the fabrication of epitaxial samples
of many materials is frustrated by chemical or lattice mismatch. This talk focuses on a new, better approach to dealing with
heterogeneous interfaces. A promising new approach–topotactic anion exchange (TAE) epitaxy. The approach is unique, with
two steps–1
st
epitaxial deposition of a precursor layer; and 2
nd
a special gas anneal to exchange the anions in the solid for others;
to ultimately yield a highly perfect epitaxial film of the product phase. Opportunities abound, as there are only two criteria to
meet: (a) The initial film is formulated to match the surface-symmetry type and lattice parameter of the substrate; (b) A thermal,
atmosphere-controlled step initiates the topotactic reaction. Ideally, compositions for TAE layers are chosen with end members
commensurate–as the reaction front passes through the solid. Cations are sessile with anions are relatively mobile. Anions are
exchanged diffusively; but because the resultant material is a different phase altogether, conversion can dramatically alter the
magneto-opto-electrical behaviors of the layers. Characterization requires finesse at the atomic level. The typical anions all have
roughly the same atomic mass, making a discernment between the two phases complicated. The results of
ex situ
and
in situ
anion exchange experiments towards an epi buffer for Si and GaN will be presented. Further discussion of analyses thus far will
be presented.
Biography
Mark A Zurbuchen is an Adjunct Professor in EE and MS&E in the prestigious DRL (Device Research Lab) under the WIN and CEGN Programs and additionally
leads the "2D Materials" sub-group and is affiliated with the "Quantum Physics & Devices" sub-group as well. He is a thin film scientist. Electron and X-ray beam
methods (XRD, TEM, synchrotron). Expertise in epitaxial films and heteroepitaxial integration. Materials design, thin film deposition, microstructural characterization,
crystallography and electrical behavior. 2D materials, oxide electronics, ferroelectrics, dielectrics, multiferroics, superconductors, nano-scale thermal behavior and
biomaterials.
mark_z@mac.comMark A Zurbuchen
University of California at Los Angeles, USA
Mark A Zurbuchen, Res. Rev. J Mat. Sci. 2018, Volume 6
DOI: 10.4172/2321-6212-C8-034