Contributions to Science, 4-2 : Nanoscience and nanotechnology research in Catalonia : Special Issue / N. Ferrer-Anglada, Guest editor

Production and characterization of nanostructured materials for optical aplications at Rovira i Virgili University

Joan J. Carvajal, Magdalena Aguiló, Francesc Díaz González

Abstract


Novel physical properties arise when the size of well-established
optical materials is decreased to the nanometer range.
This has generated great interest in all aspects of the synthesis
and characterization of such nanocrystals, from materials
for laser applications to materials for frequency conversion
phenomena. In this paper we present three new approaches
for studying these materials. Nanocrystals of laser materials
are expected to show new spectroscopic features compared
to their bulk counterparts. This has led to advances in the
procedures for the synthesis of nanocrystals of double potassium
tungstates and lutetium sesquioxides, both containing
lanthanide ions, using a sol-gel approach: the Pechini method.
We extensively characterize the structure and spectra of
these new nanocrystals with the aim of facilitating the production
of new ceramic materials with laser applications. We also
analyze the morphology and vibrational structures of the nanoparticles
produced. We synthesized also Er-doped GaN
sub-micron-sized rods on silicon (001) through the direct reaction
of gallium and ammonia in a simple chemical vapor
deposition system. This allowed us to study the unique properties
that natural electron confinement leads to in such widebandgap
semiconductors. We studied their spectroscopic
properties in depth to understand the excitation mechanisms
of lanthanide ions in such semiconductor structures, which
can lead to nearly ideal optical emissions. We recorded green
and red emissions at room temperature coming from submicron-
sized rods with excitation below the energy of the
bandgap. Finally, the formation of ordered arrays of these
one-dimensional structures is of special interest due to the
new properties that may arise when compared to individual
one-dimensional structures. At the Física i Cristal·lografia de
Materials laboratory at Universitat Rovira i Virgili (URV) we
produced two-dimensional photonic crystals of KTiOPO4, a
non-linear optical material, using an entirely new procedure
that combines bottom-up and top-down approaches. We
produced an ordered array of KTiOPO4 one-dimensional
structures using a silicon macroporous template and a KTi-
OPO4 substrate to control their orientation. We demonstrated
the physical properties of these photonic crystals: we measdiured
their third-order forbidden band, and explored their
near-IR and visible light diffraction properties.



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ISSN: 2013-410X (electronic edition); 1575-6343 (print edition)