Research On The Microstructure And Optical Properties Of Diamond-like Carbon Films

Diamond-like Carbon(DLC)film is a metastable amorphous material formed by the combination of sp~3 and sp~2hybrid bonds of carbon.It has high hardness,high wear resistance,good transparency and biocompatibility.And other unique properties.DLC films prepared by different processes have different microstructures and properties.In particular,as an optical material,DLC film has a wider band gap and a lower refractive index,and the refractive index can be adjusted within a certain range.Therefore,DLC can be used to prepare an anti-reflection film on the surface of crystalline silicon to improve the photoelectric conversion efficiency of solar cells.This paper uses magnetron sputtering deposition equipment to prepare a series of DLC films on a single crystal silicon substrate,discusses the influence of process parameter changes on the microstructure and optical properties of DLC films,and studies the effect of DLC film microstructure evolution on optical properties According to the law,the DLC anti-reflection film on the surface of monocrystalline silicon is designed.The specific work is as follows:1)DLC films with different process parameters were prepared by changing the RF power and substrate temperature,and the surface morphology and microstructure of DLC films were analyzed by SEM,AFM,XPS,Raman,etc.The effects of process parameters on the surface roughness and sp~3content of DLC films were studied.The results show that with the increase of power and substrate temperature,the content of sp~3 phase in the DLC film first increases and then decreases.Then it is determined that the optimal deposition process of DLC film is that the RF power is 200W and the substrate temperature is from room temperature to 600°C.Using ellipsometer and spectrophotometer to analyze the optical properties of DLC films,and further reveal the influence of film microstructure on optical properties.The results show that the refractive index of the film is related to the sp~3content,the higher the sp~3content,the higher the refractive index.Changing the process parameters,the refractive index of the DLC film can vary from 1.64 to 2.18.The extinction coefficient of DLC film is related to the content of sp~2phase in DLC film.The higher the content of sp~2,the higher the extinction coefficient.2)In order to further strengthen the research on the optical properties of DLC films,DLC films were prepared by changing the methane concentration to study the influence of methane concentration on the optical properties of DLC films.It was found that as the methane concentration increased,the transmittance of the DLC film showed a gradual decrease trend.When the methane concentration is below 5SCCM,the light transmittance of the film is the best.3)Based on the optimized process parameters,the FDTD software simulates DLC films with different layers on silicon and glass.The feasibility of DLC film as anti-reflection and antireflection film was studied.Adding multiple layers of DLC film on the silicon substrate can achieve multi-band anti-reflection effects in the visible light region.Adding DLC film to the glass substrate can achieve multi-band anti-reflection effects in the visible light region.