FABBRICAZIONE E CARATTERIZZAZIONE DI METASUPERFICI ORGANICHE PER DISPOSITIVI FOTONICI

The advancement of lithography played a significant role in the progress of microfabrication technology. Nanosphere lithography (NSL) is a cost-effective and straightforward method in nanofabrication that allows for parallel processing and high production rates. It has the capability to create a wide range of nanostructures and well organized 2D arrays for photonic devices. In this thesis project, we discuss our recent endeavors to expand the applications of NSL by developing strategies for fabricating nanopillar structural patterns fabricating new nanostructure (specifically PEDOT) and characterizing them through scanning electron microscopy. Utilizing the self-assembly process of colloidal microspheres or nanospheres proves to be an effective technique for creating ordered nanostructures. The use of polystyrene nanospheres as masks, in combination with nanofabrication methods, is referred to as "colloidal lithography." This project provides an overview of the fabrication of colloidal crystals and nanostructure arrays through colloidal lithography. At the outset of our research, we aimed to create a monolayer by directly applying PS nanospheres onto the PEDOT layer. However, due to the roughness issues associated with the PEDOT layer, it became necessary to employ a sacrificial layer to achieve the desired nanopillar morphology for the PEDOT. Initially, a layer of photoresist was applied onto the PEDOT layer, followed by summarizing various approaches for creating monolayer and intricate colloidal crystal structures. After the formation of the monolayer, the size of the nanospheres was reduced through a plasma oxygen treatment. Subsequently, the samples were prepared for the etching process. By employing reactive ion etching (RIE), we fabricated nanopillar structures. Initially, the photoresist was etched, followed by the etching of the PEDOT layer. Finally, the photoresist was removed from the surface using a specific solution. Subsequently, a SiOx layer was deposited onto the PEDOT layer using the electron beam evaporation technique, as for the nanofabrication strategy. Due to the iii differing properties of the photoresist and SiOx, it was necessary to adjust certain parameters. Prior to the deposition of the PS nanospheres, the SiOx layer was functionalized to enhance the formation of the monolayer. Subsequently, the size of the nanospheres was reduced using a plasma oxygen treatment. In the next step, both the SiOx layer and the PEDOT layer were etched. However, in this experiment, the SiOx layer was not removed from the surface. Creating a mask made of Polystyrene nanospheres through spin-coating is a method that shows promise but has not been extensively studied. Additionally, we thoroughly examined the process of controlled size reduction of nanospheres using an oxygen plasma machine. After analyzing the experimental data, we identified the optimal technological parameters for NSL and successfully generated a nanosphere mask on PEDOT. By reducing the diameter of the nanospheres, we were able to create nanopillar starter models of various sizes. In this study, we achieved the reduction in nanosphere size, PEDOT etching, and removal of polystyrene residues through a unified continuous process of reactive ion etching. The periodicity of the final structure was determined by the initial diameter of the spheres. To examine the surface morphology of the samples, scanning electron microscopy was employed.