Solid-state Dewetting Fabrication Of Micro-nano Structure Metasurface And Its Properties

Metasurface is a subwavelength planar periodic structure array.It can achieve a variety of functions like superlens by the flexible and effective regulation of polarization,amplitude,phase,polarization mode and propagation mode of electromagnetic wave.As an important part of metasurfaces,metal metasurfaces have attracted much attention in the field of optics and optoelectronics due to their localized surface plasmon resonance.The development of metasurface is inseparable from the research and development of micro-nano processing technologies.It is generally believed that the dewetting of metal films on an inert substrate is the simplest method to form a micro-nano structure metasurface.In the past two decades,researches on the preparation of micro-nano structures by dewetting method have mushroomed.However,the size of micro-nano structures obtained by dewetting method is mostly at the nanoscale,and their location distribution is not precisely controlled.In this paper,based on the dewetting process,Au micro-nano structure metasurface was prepared by combining the formwork substrate with the fractal crystallization of Ge films,and the effective control of micro-nano structure parameters was realized.At the same time,its optical property was investigated.The main work is as follows:1.In this thesis,the factors affecting the dewetting process of Au films on inert substrates?Si and SiO₂?were studied through constant temperature annealing in a tubular furnace,including the types of substrate,the inclined substrate,the film thickness,the annealing temperature and the annealing time.The optical properties of the formed Au micro-nano particle array were tested and verified by simulation,and the optimal parameters were selected for subsequent research.2.In this thesis,periodically distributed Au nanoparticles were obtained by studying the dewetting phenomenon of 50 nm Au films on circular pit arrays with different pit depths.It showed that the templated substrate can control the solid dewetting of the film by generating periodic changes in the initial curvature of the film.The initial position of dewetting and the direction of the surface diffusion flux can be accurately controlled,so that the dewetting process becomes more uniform.3.In this thesis,the effect of fractal crystallization of Ge films on the dewetting of Au films was discussed by studying the dewetting phenomenon of Au/Ge bilayer films.It was confirmed that the addition of Ge thin film is conducive to the formation of large-size Au nanoparticles.4.In this thesis,the dewetting process of Au/Ge bilayer films on the templated substrate was studied by combining the templated substrate and the fractal crystallization phenomenon of Ge films.An array of circular pits with a depth of 800nm was fabricated on the SiO₂ substrate by photolithography and etching,then 20 nm Ge film and 50 nm Au film were deposited.After annealed at 900°C for 3h,large-size Au particles periodically arranged at the center of the mesa and small-size particles distributed inside the pit were obtained.After testing,this sample had a significant LSPR peak at 531 nm,and a scattering peak of large Au particles was observed at a wavelength of 2300 nm.