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Materials Science Division |
HighlightsPhoto-Ferroelectric HeterojunctionsPhoto-Ferroelectric Heterojunctions Scientific Achievement Fundamental
studies have been
initiated in the IMG to manipulate band structure in a light-absorbing
semiconductor using the polarization from an adjacent ferroelectric
layer, so
as to explore mechanisms that may influence light-to-electricity
conversion. This
research involves growing epitaxial
SrRuO3 (SRO) electrode layers on transparent
single crystal SrTiO3
(STO) substrates, followed by growing an epitaxial PbTiO3
(PTO)
film, and then a semiconducting TiO2 or Cu2O
nanoparticle
layer, and finally a transparent electrode layer such as ITO to
complete the
structure. By
controlling the PTO
polarization direction we will be able to determine the effect of the
ferroelectric (FE) layer on the semiconducting properties (carrier
separation
and transport) of the neighboring TiO2 or CuO2. Equally importantly, the
influence of
nanoparticle size on band bending across the interface will be
investigated. Several
samples have been
prepared and their microstructures have been characterized by using
SEM, AFM
and x-ray diffraction. We
will measure
optical absorption and charge conversion processes for these
heterostructures
to understand the fundamental processes responsible for
photon-to-electrical
transduction phenomena. Significance Utilization of pan-chromatic light absorption and avalanche ionization in nanoscale semiconductor materials may provide the basis for greatly increase efficiency for solar energy conversion. However, one of the biggest challenges to performance of such “3rd generation solar cells” is to develop effective strategies that enhance charge separation and increase current output. Band realignment effects at a ferroelectric/semiconductor interface, induced by the spontaneous polarization in a pyroelectric or ferroelectric material, may provide a way to promote carrier separation and extraction from the semiconductor. Performers 
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