Synthesis Of Size-controllable Ag Nanoparticle Arrays And Its LSPs Enhanced Light Emission Of Oxidized Amorphous Silicon Nitride Films

Silicon-based optoelectronic integration is a potential solution for the sustainable development of the integrated circuit industry.In this research,to further improve the light emission efficiency of a-SiNx:O films,size controllable Ag nanoparticle arrays were inserted between Si substrate and a-SiNx:O film.Ag nanoparicle arrays were prepared by polystyrene nanosphere lithography(NSL)and the size was controlled to make the LSP extinction wavelength better match the light emission wavelength of a-SiNx:O.The PL enhancement factor of a-SiNx:O films with Ag nanoparticles was more than 4-fold compared with that of a-SiNx:O on bare substrate.Further more,the time-resolved PL(TRPL)spectra confirmed the coupling between a-SiNx:O excitons and LSPs.The coupling process and enhancement mechanism were analyzed.We also calculated the electromagnetic field distribution around the Ag nanoparticles and the near-filed enhancement effect is confirmed.The main conclusions and innovations are summarized as follows:1.Ag nanoparticle arrays were inserted between substrate and a-SiNx:O film.The nanoparicle arrays were prepared by polystyrene nanosphere lithography(NSL).By selecting an appropriate diameter of nanosphere and thickness of Ag deposited,the nanoparticle arrays with controllable size and ordered arrangement were obtained.Morphology parameters were measured by atomic force microscopy(AFM).Hexagonal arrays of Ag nanoparticles are obtained by single-layer PS masks.Hexagonal-center arrays of Ag nanoparticles are obtained by double-layer PS masks.Besides,periodical Ag nano-ring arrays are fabricated by NSL method with single-layer PS masks.We proposed a possible mechanism to explain the formation process.Steps effect between PS and substrate and high kinetic energy of Ag atoms both contribute to the formation of Ag nano-ring arrays.The extinction spectra of Ag nanoparticles show that LSP resonance wavelengths can be controlled from 402 nm to 457 nm.We also use Maxwell-Gamett theory to calculate the extinction peak.The results are consistent with experiment results.2.A-SiNx:O films with different Si/N ratios were prepared by a plasma enhanced chemical vapor deposition(PECVD)system.Based on the extinction peak of hexagonal arrays of Ag nanoparticles,a-SiNx:O with blue emission was chosen as active layer.PL spectra show there is a 4 fold enhancement at the peak 473 nm after the introduction of hexagonal arrays of Ag nanoparticles.The extinction peak at 465 nn for a-SiNx:O with hexagonal array of Ag nanoparticles confirms the coupling between active layer and Ag arrays.Electromagnetic field distribution around the Ag nanoparticle arrays was calculated by the finite element method.Calculated results show that LSP mode of hexagonal arrays of Ag nanoparticles is dipole mode.Near field enhancement effect of LSP is confirmed by the calculation.Time resolved photoluminescence was conducted for a deeper understanding of the enhancement mechanism.The TRPL data can be fitted by a biexponential function.The long component of a-SiNx:O without Ag is 10.40 ns and the short one is 2.14 ns.After the introduction of Ag nanoparticle arrays,the long component is reduced from 10.40 ns to 7.28 ns and the short component is reduced from 1.760 ns 1.60 ns.It indicates that the recombination rate is increased after the introduction of Ag nanoparticle arrays.LSPs induced by Ag nanoparticle arrays provide an additional,high-rate recombination channel for excitons generated in a-SiN:O,and speeds up the recombination process.Energy of LSPs can be extracted as photons which results in the enhancement of PL.