Study On Gradual Refractive Index Si_xH_y Films And Their Application To Rugate Filters

Gradual refractive index films overcome the jump characteristics and instability of conventional films caused by the presence of interfaces between layers,not only increasing the damage threshold of the film but also reducing the degradation of the properties.It also offers better prospects for the preparation of laser films.In addition,the continuous change in refractive index(replacing)materials that are lacking in the design of the film,increasing the flexibility of the film system design,and providing better adhesion and less stress.Silicon hydride,an unstable hydride of silicon,is used as a research material for gradual refractive index films,which are easily prepared with periodic changes in refractive index,subject to process parameters.Silicon hydride,which is an unstable hydride of Silicon is used as research material for gradual refractive index films prepared with periodic changes in refractive index subject to process parameters.It has the advantages of(facitilitates)small infrared absorption coefficient,high refractive index and wide transparency zone.and is widely used in the preparation of near-infrared filters,and is also often applied in thin-film solar cells,displays and sensors.This paper uses Matlab software to calculate the refractive index distribution profile of Si_xH_y gradient refractive index films.Our aim is to study the design principle of variable refractive index films and design rugate filters using the Rugate design module of Macleod film system design software.Rugate filters with a cut-off band depth of OD4 and a cut-off band width of 30 nm at 1064 nm in the near-infrared band were designed with a transmittance greater than 95%.The process parameters such as hydrogen flow rate and target sputtering power were analyzed to study the effects of process variations such as target power,plasma source power and filling volume on the optical properties of the films in magnetron sputtering.The optical constants of the hydrogenated silicon monolayer films prepared under different process parameter conditions were tested.The optical constants of the hydrogenated silicon films were accurately fitted using Optilayer software.The effects of different preparation processes on the optical constants was investigated.The refractive index variation was determined by varying the hydrogen flow rate.Our results show that the refractive index variation range is2.91-3.67 for Si_xH_y.Based on the influence of the refractive index variation profile and process parameters on the refractive index,a model of the relationship between the process gas flow rate,deposition rate and refractive index was established.According to parameters of the mode,the accuracy of the model was verified by preparing Si_xH_y films with gradual refractive index.