Since the discovery of the perovskite-type materials with their unique ABX3 cubic lattice structure in
1839, there has been a proliferation of compounds with broad fields of application. When perovskite
thin films are less than 100 nm thick, extraordinary optical, magnetical, electrical and chemical
properties can be obtained with specific structural and compositional designs. This project investigates
two perovskite-type thin films with promising plasmonic and magnetic properties: strontium niobate,
SrNbO3, and strontium ferrite, SrFeO3. The aims are developing alternative methods to manipulate the
structure and performance of the perovskite thin films for future device developments, including
surface-enhanced Raman spectroscopy, water-splitting photocatalysts, random-access memories, and
solid oxide fuel cells.
Strontium niobate thin films were fabricated by pulsed laser deposition technique. The films were
grown on two substrates, magnesium oxide and strontium titanate. The following strain analysis shows
that thin films grown on magnesium oxide substrates have more unit cell distortions and defects, such
as misorientations. Gold nanoparticle decorated strontium niobate thin films were also in situ grown.
The topographical analysis shows that gold nanoparticles' morphology and growth mechanism above the strontium niobate surface are significantly influenced by the substrate selected. The stain analysis
reveals that the strontium niobate layer conducts the strain generated at the substrate interfaces.
Controlling the residual strain could be an alternative method for tailoring the morphology and
plasmonic properties of gold and other metallic nanoparticles.
Strontium ferrite thin films were also deposited in controlled oxygen pressure environments. Since
strontium ferrite has an oxygen-deficit brownmillerite variant phase, the oxygen pressure is controlled
during different fabrication processes. Based on the structural and optical analysis, it has been proved
that the oxygen partial pressure during the cooling process is the main driving factor introducing the
phase transformation between perovskite phase and brownmillerite phase.