Broadband Absorption Of Ag/SiO₂ Multilayers Based On Self-Assembly And Dynamic Shadow Deposition

In recent years,metamaterials have been proven to have unusual electromagnetic properties and enormous potential value in many fields.Among them,plasma nanostructures have played an important role in optical sensing technologies such as metamaterials and localized surface plasmon resonance?LSPR?.In this thesis,a novel plasma structure/material was designed by combining the self-assembly of nanospheres with the dynamic shadow growth method using a tilted-angle deposition technique.The morphology and size of the structures were tested and characterized,and the transmittance and reflectance were measured.The simulation calculations and experimental studies show the optical properties of the structure and elucidate its broadband absorption mechanism.The specific research content is as follows:1.The Polystyrene?PS?monolayers of different diameters?350 nm,500 nm,750nm,and 1000 nm?were prepared on clean,hydrophilic glass slides or silicon wafers by modified air/water interface self-assembly techniques.The results show that the obtained PS monolayer has the advantages of large area,high film quality,and can be used as a template for further fabrication of plasma metamaterials.2.Ag/SiO₂ patches of different shapes and areas were fabricated on the PS monolayer film through dynamic shadowing deposition.The MATLAB program was used to simulate and predict the surface morphology of the spherical film patches.The effect of the tilt angle,deposition times,and deposition thickness on the morphology and optical properties of the PS monolayer film were explored through experiments.In addition,the Finite-Difference Time-Domain?FDTD?method was used to simulate the deposited structure and explain its optical properties.3.The target materials Ag and Si O₂ were alternately deposited on the self-assembled PS monolayer template by electron beam vacuum evaporation.The diameters of the PS spheres on the template and the number of Ag/SiO₂ deposition cycles were systematically studied for the sample's optical properties.The results show that when the number of deposition cycles with 750 nm diameter PS sphere template is 7,the absorption of obtained sample with the wide wavelength range of 350-850 nm can reach over 92%,and the obtained samples have surface-enhanced Raman scattering?SERS?effect.The research provide new ideas for the design and preparation of novel broadband absorbing materials,which can provide references for applications in the fields of solar cells and stealth materials.