Study On Reflective Nanophotonics Structure GaAs Photocathode

Nanophotonics structural materials are widely used in optoelectronic devices due to their excellent optoelectronic properties,and they use the Mie scattering optical resonance effect to realize the regulation of light.The GaAs nano-pillar array structure has the excellent characteristics of nano-photonics structure,and the GaAs photocathode prepared from it has the advantages of high quantum efficiency,low dark current and long working life.Therefore,in this paper,a single-layer mask layer on the surface of the GaAs substrate was first prepared by different masks and different methods,and then the GaAs nano-pillar array structure was prepared by inductively coupled plasma（ICP）etching.The Cs/O activation experiment was carried out on the nanopillar array structure,and the reflective nanophotonics structure GaAs photocathode was prepared.The preparation of the GaAs nano-pillar array structure is mainly divided into two parts,namely,the preparation of the mask layer and the etching of the nano-pillar array.In this paper,the principle of self-assembly at the water-air interface is used to prepare a polystyrene（PS）nanosphere monolayer mask layer by LB film pulling technology,and the influence of the proportion of methanol added on the self-assembly is analyzed.300nm PS nanosphere single-layer mask layer,by studying the influence factors such as gas selection,added gas flow rate,etching power and etching time,to find the optimal process parameters for mask layer etching,and then use this as the Mask-etching GaAs obtains a GaAs nano-pillar array structure with a diameter of 100 nm suitable for dipole resonance and a diameter of 230 nm suitable for quadrupole resonance.In addition,for the preparation of fixed-size nanoarray structures,the nanoimprint method has its unique advantages.The diameter of the nanoimprint template used in this paper is 110 nm,and a layer of Si O₂ film is grown on a GaAs substrate,and then A layer of polymethyl methacrylate（PMMA）is spin-coated on it,the pattern of the nanoimprint template is transferred to the PMMA,the PMMA outside the pattern is removed by selective etching,and then different materials are applied with different masks.After etching,the GaAs nano-pillar array structure is finally obtained.Finally,the optical test and activation test were carried out on this structure,and the reflective nanophotonics structure GaAs photocathode was obtained.The optical resonance effect of the nanoarray structure is verified,and the reflectivity is significantly reduced,which lays the foundation for its application in the field of photocathode.