The Propagation Properties Of Surface Plasmon Polaritons In Nanocavities And The Synthesis And Characterization Of The Nanostructures Of Molybdenum Oxides

Surface Plasmon Polaritons (SPPs) are the transverse magnetic (TM) waves that can propagate along the metal-insultor interfaces generated by the collective oscillations of surface free electron in the metal induced by the external photons. SPPs can break the traditional optical diffraction limit, and possess novel properties of sub-wavelength localization, near-field enhacement and surface confinement. SPPs have important application prospect in nanophotonics, controlling of near-field nanobeam, sub-wavelength optical waveguides, data storage, super-resolution imaging, solar cell and negative index material. Molybdenum oxides are important semiconductors semiconductor materials with indirect wide bandgap, and the element of Mo has multiple valence states, thus many compounds can be formed, such as MoO, MoO2, MO2O3, MoO3, Mo4O11. In these compounds, the MoO2and MoO3has obtained extensive researchs of researcher due to their high chemical stability and abroad application foreground.In this M.S. Dissertation, we mainly discuss the propagation properties of SPPs in nanocavities, the synthesis of transition metal oxides of MoO2and MoO3and the related applications of optoelectronic devices based on MoO3nanobelts are introduced. The major research contents and achievements made in this thesis are summarized as follows:(1) Utilizing the idea that filter property can be obtained by resonance characteristics of nanocavity in MIM waveguide, we propose a novel plasmonic sensor of circular nanocavity embedded with an Ag nanocube based on the metal-insulator-metal (MIM) waveguide. The filter was characterized by the finite-difference time-domain method. Since the tilted Ag nanocube breaks the symmetric steady-state magnetic field distribution, a new resonance mode occurs in the circular nanocavity. The resonance depends on the rotation angle and length of the cube. The MIM waveguide with a circular nanocavity embedded with a tilted Ag nanocube is more sensitive to small refractive index changes that fill the nanocavity than the MIM waveguide with a empty circular nanocavity and the MIM waveguide with circular nanocavity symmetrically embedded with an Ag nanocube. A potential application to biosensors has therefore been established.(2) In this thesis, the MoO3nanobelts with a width of about200nm and the MoO2nanoparticles with different sizes have been synthesized by hydrothermal method, and the influence of PVP concentration to the composition and morphology of hydrothermal product is investigated. In addition, the Cu atoms have been inserted successfully in layered structure of MoO3nanobelts, and we also study the current-voltage (â… -â…¤) characteristics of optoelectronic devices based on single and multiple MoO3nanobelts under the condition of different illumination. The research results indicate that the final product synthesized by hydrothermal method is orthorhombic phase of MoO3nanobelts when PVP concentration is lower; With the increase of PVP concentration, the obtained product will be MoO2nanoparticles, moreover, the higher concentration of PVP lead to the smaller size of MoO2nanoparticles; The crystal structure and morphology of MoO3nanobelts is unchanged with the embedding of Zero-valent copper; Compared to the optoelectronic devices based on multiple MoO3nanobelts, the optoelectronic devices based on single MoO3nanobelt has a smaller ohmic contact between the MoO3nanoribbon and Au electrodes, and are more sensitive to light, which have a potential application in photoelectric detector, biological and chemical sensors, and other fields.