Growth And Optical/electrical Characterizations Of Transparent Conductive Oxide ITO Thin Film And ITO/Au Hybrid Structure

Noble metals such as gold and silver have been proved to be possessing excellent plasmonic properties in the visible range due to their high carrier concentration. However, some drawbacks of noble metals like relatively high optical absorption, non-adjustable electrical and optical properties, large magnitude of real part permittivity and imcompatibility with standard CMOS process have limited their further applications in near-infrared (NIR) wavelength range, especially near the communication wavelength. Under this circumstance, transparent conductive oxides (TCOs), which have been predominantly used as transparent electrodes in flat panel display, as well as in photovoltaic devices, re-attract people’s attention for new applications. Compared with their metal counterpart, TCOs exhibit several advantages:their electrical and optical properties can be tuned by doping or deposition parameters optimazation due to their non-stoichiometric characteristics, the metal-like property in NIR range provide them the same magnitude of real and imaginary part permittivity implying lower optical losses, the fabrication of TCOs is compatible with standard CMOS process making it possible for on-chip integration, and their relatively high mechanical and chemical stability guarantee the reliability of related devices. All these advantages indicate TCOs as promising plasmonic materials to be applied in the field of nano-photonics, metamaterials and transform optics et al.This thesis is based on the pulsed laser deposition (PLD) technology and magnetron sputtering technology to explore the influence of deposition conditions on the microstructures, electrical and optical properties of indium tin oxide (ITO) thin films. Nano-structured ITO pillar arrays and ITO/Au hybrid structures have also been fabricated to study their potential plamonic applications. The main contents are listed as follows:1. The procedures of depositing ITO thin films via PLD and magnetron sputtering system were firstly introduced, followed by discussions of two methods used to obtain nano-structured ITO pillar arrays. Subsequently, various measurements of ITO films, nano-structures and ITO/Au hybrid structures were also introduced.2. The influences of deposition conditions (substrate temperature and oxygen partial pressure) on the microstructures, electrical and optical properties of ITO thin films were systematically explored. Details of fabricating nano-structured ITO pillar arrays and the plasmonic properties were also investigated and discussed.3. Configurations of model GES5E spectroscopic ellipsometry and the equipped fitting software WinElli Ⅱ were introduced. The optical models used to describe the optical behavior of different materials and the methods of approximation were listed and discussed. The optical models and the film configurations were investigated to retrieve the optical permittivity and thickness of ITO thin film, Au thin film and ITO/Au hybrid thin films.4. Relationships between properties of ITO/Au hybrid structures and the thickness of intermediated Au thin film were explored and discussed. Meanwhile a new effective medium approximation method was introduced and used to describe the overall behavior of the ITO/Au hybrid structures. Followed was the discussion of the potential applications of the ITO/Au hybrid structures.