Preparation And Properties Of Diamond Like Carbon Films And Their Composite Structure

Diamond like carbon film has excellent comprehensive properties as a carbon material.It combines the advantages of diamond film and graphite,including high hardness,low electrical resistivity,high visible light transmittance and good wear resistance.Its application covers many fields such as mechanics,electricity,optics and medicine.Adjusting the preparation process of the diamond like carbon film to obtain higher transmittance in visible region and good comprehensive performance is of great significance to its application.In this thesis,diamond like carbon?DLC?films were deposited on glass substrates by magnetron sputtering using graphite as the target.The effect of the preparation parameters on the optical transmittance of the DLC films was investigated.Results showed that all the deposited films were amorphous.Within a certain range,the increase in sputtering power and deposition time induced the decrease in transmittance of the DLC films in visible region.In order to further study the effect of nitrogen flow rate on the structure and properties of DLC films prepared by magnetron sputtering,nitrogen was introduced to prepare nitrogen-doped diamond like carbon films.The morphologies of the films under different nitrogen flow conditions were characterized by atomic force microscopy.Microstructures,valence state of elements and transmittance of the samples were analyzed by Raman spectrometer,X-ray photoelectron spectrometer and spectrophotometer.Results showed that the optical transmittance of the films greatly increased when 2 sccm nitrogen was employed.And the nitrogen content,sp³ bond percentage and I_D/I_G in DLC film were 5.88%,64.65%and 1.81,respectively.The optical transmittance of N-doped DLC films in the visible range was about 96%.As the nitrogen flow rate continued to increase,the optical transmittance of the films decreased.After annealing for 2 h,the optical transmittance of DLC films without N-doping decreased slightly,while the optical transmittance of N-doped DLC showed little change.Finally,the silver film was introduced to prepare DLC/Ag/DLC composite film with high visible light transmittance and low near-infrared transmittance.By changing the growth conditions during the preparation of DLC/Ag/DLC composite films by magnetron sputtering,including the sputtering power of inner layer DLC,silver layer and outer layer DLC,deposition time of each layer and nitrogen gas flow rate,the influence on the light transmission properties of the films were explored.The results showed that the DLC films has excellent optical properties.The optimal parameters of sputtering power,sputtering time and gas flow rate were set as 60 W,600 s and 2 sccm N₂/18 sccm Ar for the inner layer DLC film;30 W,70 s and 20 sccm Ar for the silver layer;60 W,150 s,2 sccm N₂/18 sccm Ar for the outer layer DLC film.The as-prepared DLC/Ag/DLC composite film exhibited a transmittance of 71.9%?550 nm?in the visible range and 39%?1100 nm?in the near-infrared range as well as good electrical properties.The optical transmittance of DLC/Ag/DLC composite films with different thicknesses was simulated by FDTD software.The simulation results showed the same trend as the experimental results.