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This thesis presents the fabrication of Sn-doped In2O3 nanostructures on a 50 nm thick SiN membrane and their characterization using monochromated electron energy loss spectroscopy (EELS). Rapidly annealed triangular structures of varying thicknesses (71 nm and 32 nm) and lengths (between 400 nm and 1200 nm) unveil a structural crystallization, as well as a blue-shift and narrowing of surface (first and second order modes) and bulk plasmon peaks as the free carrier concentration increases. Bulk peak positions shift from 515+/-39 meV to 628+/-36 meV for 71 nm thick triangles. The second order surface plasmon modes exhibit a greater blue-shift after annealing (93 meV) than the first order modes (36 meV), consistent with the trend found in boundary element method (BEM) simulations using ellipsometry data. The Richardson-Lucy (RL) deconvolution algorithm is employed to improve the effective energy resolution and reveal these surface plasmons as well as a substrate phonon at 100+/-19 meV. Low-loss EELS spectra for 32 nm thick triangles potentially show a blue-shifting bulk plasmon from 751+/-42 meV to 912+/-42 meV with decreasing triangle size. STEM imaging of the triangle structure cross-sections may show a clustering of oxygen vacancies and indium atoms that could be responsible for this blue-shift. Core-loss EELS spectra between 380-550 eV using the oxygen K-edge signal provide evidence of a change in the bonding across the ITO/SiN interface, although its effect on the electrical properties requires further investigation. Thesis Master of Applied Science (MASc) The push towards smaller, faster electronic devices and sensing equipment has accelerated research into manipulating oscillating groups of electrons, or plasmons. So far, the building blocks of these next-generation systems use metals such as gold and silver; however, new materials must be explored for them to be commercially viable. Thin continuous films of transparent conductive oxides (TCOs) such as Sn-doped Indium Oxide (ITO) are already widely used in conventional silicon-based technologies, and in this work ITO nanostructures are fabricated to visualize their plasmonic response, in the hopes that they could be tailored towards plasmonic devices. The relationships between how these plasmons evolve with varying dimensions and the application of heat are explored using electron microscopy.