Optical Properties Of ZrO₂ Films Prepared By RF Magnetron Sputtering

With its advantages of excellent mechanical properties,high insulation,special optical properties and good corrosion resistance,ZrO₂has replaced the materials with large loss of light and short service life.It has become the main material of important components of optical communications and optical fiber connectors in modern information optics and optoelectronic technology,and has great development prospects in the field of information communication and electronics.In this paper,ZrO₂is selected as the target to fabricate the thin films by RF magnetron sputtering.By changing the process parameters and annealing treatment,the influence on the optical properties and microstructure of the film is studied,so as to provide reference for the engineering design and practical applications of the material.Through the FJL560C12 RF magnetron sputtering coating system,the ZrO₂thin films were prepared on the K9 glass and polished Si slices by using a target of the same composition with a purity of 99.99%.The effects of process parameters（deposition time,deposition pressure,sputtering power）on the optical properties and microstructure of the ZrO₂thin films were analyzed and studied.（1）When the deposition time was 120 min,the maximum average transmittance of 87.27%and the maximum refractive index of 2.26 in the ranges of 200-1000 nm of the ZrO₂films were obtained.（2）The deposition rate of ZrO₂films decreased from 2.47 nm/min to1.64 nm/min as the deposition gas pressure increases from 0.2 Pa to 0.8 Pa.The average transmittance of ZrO₂films in the 200-1000 nm band varies from 78.80%to87.27%,and the average refractive index varies from 2.17 to 2.26.When the deposition pressure is 0.2 Pa,the maximum average transmittance of 87.27%and the maximum refractive index of 2.26 were achieved.At this time,the film has is the lowest roughness,since the particle distribution on the surface is uniform and the structure is dense.As deposition gas pressure increases,the direct band gaps of 5.59,5.59,5.60,and 5.62 e V of the ZrO₂films can be found,while the corresponsive indirect band gaps are 6.06,6.06,6.08,and 6.08 e V,respectively.The deposition pressure has a certain but limited effect on the bandgaps.The X-ray diffraction peaks of（111）,（220）and（311）for the ZrO₂films increase with decreasing deposition pressure.（3）While the sputtering power increases from 60 W to 120 W,deposition rate of the ZrO₂films increases from 0.28 nm/min to 2.58 nm/min.The average transmittance of ZrO₂films in the 200-1000 nm band varies from 64.41%to 87.27%,and the average refractive index varies from 2.00 to 2.26,whose maximum values were achieved at 100 W,respectively.The film has the lowest roughness at this time.As the sputtering power increases,the direct band gaps of ZrO₂films gradually increased from 4.65 e V to 5.58,5.59,5.60 e V,and the indirect band gaps of ZrO₂films gradually increased from 5.82 e V to 6.03,6.06,6.08 e V.Diffraction peaks for ZrO₂（111）,ZrO₂（200）,ZrO₂（220）,ZrO₂（311）and ZrO₂（211）can be found at various sputtering powers.In order to further optimize process parameters for tthe ZrO₂,the films with optimized optical properties,deposited at 0.2 Pa,100 W for120 min,were post-heat treated by annealing.The effects of annealing temperature and annealing time on the optical properties and microstructure of the ZrO₂films were analyzed and studied.The annealing treatment enhances the average transmittance but has little effects on the average refractive index of the ZrO₂films.Both the average roughness（Ra）and the root-mean-square roughness（Rq）increase with the increasing annealing temperature,while both roughness decrease firstly and then increase as the annealing time is prolonged.