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Lia's Project Page - RISE summer 2004 |
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Intern: Lia Bregante, UCSB
Mentor: Sean Keane
Faculty Supervisor: Susanne Stemmer
Department: Materials |
THE EFFECT OF MICROSTRUCTURE ON THE ELECTRICAL PROPERTIES OF STRONTIUM TITANATE THIN FILMS
As a prototype, incipient ferroelectric material having a perovskite
structure and exhibiting a nonlinear, electric field tunable dielectric
constant at very low temperatures, SrTiO3 has potential applications in tunable
microwave devices that must operate at such temperatures. When thin films of
SrTiO3 are deposited by rf sputtering on epitaxial Pt, their microstructure is
seen to vary with the growth temperature and length of annealing time of the Pt.
A second sputtered film itself, the Pt is grown on a sapphire (Al2O3) substrate
and is used in this case as a bottom electrode, as is commonly done in
ferroelectric devices and integrated capacitors because of its known chemical
stability and high conductivity. Atomic force microscopy (AFM) allowed for the
examination of the microstructures of both the Pt and SrTiO3 thin films.
More specifically, analysis of RMS surface roughness, average grain size, and
grain orientation yielded data that provided insight into the relationship
between the microstructures of the two materials, and the effect of
microstructure on the dielectric properties of the SrTiO3 thin films.
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