Based On The Template Of Subwavelength Microstructure Preparation Antireflection Performance

The simple method is developed to generate large-area antireflective sub-wavelength structures (SWSs), in which the two-dimensional colloidal crystals or stochastic island film as the masks. After reactive ion etching with CF4, Ar, O2, periodic SWSs and aperiodic SWSs were formed.On the one hand, we developed a coating procedure for continuous formation of 2D particle arrays, analyzed the parameters determining the array growth, developed an experimental apparatus, and produced centimeter-sized monolayer arrays from small polystyrene particles. It was found that the uniformity and spatial extent of colloidal self-assembly monolayer were significantly influenced by the experimental parameters such as (1) the match of between withdraw velocity and the colloid concentration, (2) the large impurity particles containing in colloid, (3) the substrate surface roughness, hydrophilic, hydrophilic stability, and so on. We have observed a hexagonally well-ordered packing colloidal monolayer in a relatively large area (2* 2cm), low defect density. The technique exploits the self-assembly of uniformly sized colloidal micro-spheres on the surface of a substrate followed by reactive ion etching (RIE) unit operating under O2 gases that converts the micro-spheres non-closed-packed colloidal crystals. We report the systematic dependence of the dimensions of the polystyrene particles on the duration of the exposure to RIE. The samples were then exposed to reactive ions in an RIE unit operating under a mixture of CF4 and Ar gases. The patterns of the masks can be accurately transferred onto the substrates using RIE, as the periodicity of the nano-pillar array is consistent with that of the mask. By the experimental result, the RIE etching is isotropic, leading to the formation of pyramid like microstructures whose sizes and aspect ratios are determined by the template PS sphere diameter and the RIE etching time. This etching process practical aspect is relatively low at about 2:1. The templated periodic SWSs exhibit broadband antireflection properties, but due to insufficient etching depth effects caused by poor antireflective property.On the other hand, a simple lithographic method is developed to generate large-area antireflective stochastic sub-wavelength structures, in which the metal (Ag/Au) island films are used as masks. Using dip coating and high temperature processing, stochastically arranged Ag/Au islands were fabricated on Si substrates. The uniformity and spatial extent of self-assembly stochastic island films were significantly influenced by the experimental parameters such as concentration, withdraw velocity, deposition times, and so on. And the array of the nanodots is used as etch mask for reactive ion etching (RIE) to form aperiodic SASs on the Si surface unit operating under CF4 and Ar. The measured reflectivity was decreased from 40% for polished Si to 5% for Si aperiodic tapered SASs with different heights generated by different etching time.Overall, due to two-dimensional colloidal crystal template size, defect density, and isotropic reactive ion etching of silicon dioxide has led to periodic SWSs micro-structure of the preparation of small size, cylindrical sub-wavelength the shortcomings of array is not deep enough. These two points have limited the use of this approach large scale synthesis of anti-reflection properties with periodic sub-wavelength microstructures. The aperiodic SWSs based gold stochastic island mask is also not enough depth, with the result that antireflection performance is highly restricted. The templated stochastic SWSs exhibit excellent broadband antireflection properties based on silver island mask. And this method has a short cycle, low cost, high reproducibility and easy synthesis of large area SWSs.