Study On The Two-dimensional Periodic V-shape Metal Plasmon Resonance Structure

Surface plasmon resonance(SPR),which generated by the interaction between light and metal nano structure,has become a hot subject.With the development of plasmonics and nanotechnology,SPR shows wide application prospects in medical treatment,material science,photoelectric sensor and other fields.And the metal grating has always been used as a model to study the interaction between light and periodic metal structure.According to predecessors' research results,a V-shape metal grating which can generate Fano resonance is designed and optimized based on the anisotropic etching properties of 100 crystalline silicon and template stripping of metal layer.Based on the finite element analysis method(FEA),simulation software COMSOL Multiphysics is used to analyze the V-shape metal grating.The parameters of the structure(such as thickness of silicon substrate and film above it,duty ratio and period of the grating,etc.)are optimized to get better performance of the electromagnetic enhancement.The field enhancement factors of V-shape metal unit and periodic grating structure are compared together.Results show when the phase of surface plasmon resonance couples with the local surface plasmon resonance,Fano resonance will be generated,which will further enhance the electromagnetic enhancement.In addition,the variable gap between the metal tips,which leads to the effect on the resonance wavelength and the field enhancement factor,is also studied.Under the precision of electron beam lithography(EBL)and wet etching,gap between the metal tips can be controlled to 10 nm,the field enhancement factor can reach more than 1000,and smaller the gap is,greater the field enhancement factor will be.On the basis of numerical simulation,V-shape metal grating is manufactured on siliconon-insulator(SOI)wafer,methods such as chemical vapor deposition,EBL,wet etching,electron beam evaporation are used in the fabrication process.Anisotropic etching is used to get a reproductive and controllable nano size metal gap.After the process of electron beam evaporation and template stripping using an adhesive backing layer(NOA 61,Norland Products Inc.),metal grating can be created.This kind of metal grating expands the electromagnetic enhancement regions and ensure a high field enhancement factor.In addition,by bending the transparent elastomer,the gap between the metal tips can be controlled,leading to the effective modulation of the resonance wavelength and the field enhancement factor.It has a great application prospect in the field of high sensitive multicomponent detection.