Fabrication of Au/TiO_x Nanoislands Systems by a Solid State Thermal Dewetting for Plasmonic Solar Cell applications

We report on the nucleation of Au nanoislands onto TiOx seed films surfaces which occurred in consecutive steps. Firstly, TiOx thin films were grown on quartz substrates reactively by e-beam evaporator and then thermally annealed at different temperatures, ranging from 300 °C to 900 °C. Subsequently, a nano- film of Au was deposited on the top of these annealed TiOx surfaces. The stacked Au/TiO2 samples were then post-annealed at a temperature of 600 °C for 1 hour, to study the thermal dewetting properties and the influence of the different TiOx morphologies on the formation of Au nanostructures and their plasmonic response. These Au/TiOx dual-systems were characterized accordingly to probe their topological, morphological, structural, and optical properties. The thermal dewetting effects on these systems were found to be more impactful at high temperatures (> 500°C), where the Au nanoparticles size distribution was found to follow a Gaussian distribution centered around 30 nm. Finally, the absorption peak for Au nanoislands has shown a localized surface plasmon resonance close to 520 nm, along with a broad shoulder peak and a strong tail, thereby reflecting the wide distribution of the formed Au nanoparticles sizes. The integration of these Plasmonic systems into planar solar cell has demonstrated an increase up to 35.51 % in terms of the photocurrent generation and was found to be Au size and surface density' dependent.