Study On Composite Antireflective And Antistatic ITO/MgF₂ Film Coated On Space Solar Cell Glass Cover

MgF₂ film is usually used as an antireflective film on the space solar cell glass cover plate because of its excellent transmittance,but because of its high resistivity,when the satellites encounter solar storms and other charged particles bombardment in the space environment,the surface of MgF₂ antireflectived solar cell glass cover will gather charge,which leads to the unevenly charged of the surface.In order to achieve an equipotential surface,the surface of the MgF₂ film is coated with a layer of indium tin oxide?ITO?anti-static film.In this paper,the ITO/MgF₂ composite films were designed by TFCalc software.On the basis of film design,the optimal thickness and the optimum plating process of the composite films were studied.Then the process of preparing ultra thin ITO film by argon ion angle bombardment thinning method was studied.And the ITO/MgF₂ composite films prepared by the two methods were compared and analyzed.The transmittance curves of single layer MgF₂ film and ITO/MgF₂ composite films were investigated by TFCalc software.With the increase of the thickness of MgF₂ film,the average transmittance of single layer MgF₂ film and ITO/MgF₂ composite films in the visible light range?400?800 nm?changed periodically.With the increase of ITO film thickness,the average transmittance of the composite films reduced monotonically.The ITO/MgF₂ composite films were fabricated by electron beam evaporation.The study of deposition process of ITO anti-static layer found that,the optical propertie of composite films is better but the electrical propertie is worse by decreasing the deposition rate of ITO,the increase of deposition temperature could improve the optical and electrical properties of the composite film,with the increase of working pressure,the optical and electrical properties of the composite films are improved first and then worse,when the working pressure is 2.3×10^-2Pa,the composite films has the best optical and electrical properties.The optimum deposition process of ITO film is deposition rate of 0.05 nm/s,deposition temperature of 400?,working pressure of 2.3×10^-2Pa.On the basis of this,the continuity of ITO anti-static layer was studied.When the ITO film thickness was 10 nm,the surface layer of ITO film was substantially continuous and its surface sheet resistance was 1.76 K?/?which met the design requirements,the average transmittance of ITO/MgF₂ composite film in visible range reached 89.88%,which can be used as the optimal design thickness of the ITO antistatic layer on the surface of the MgF₂ antireflective film.The MgF₂ antireflective layer of the composite films was then studied.The average transmittance of the composite film in the visible region has a maximum value of 92.27%when the MgF₂ film thickness was 90 nm and the deposition rate was 0.1 nm/s.The ITO/MgF₂ composite films were then prepared by argon ion angle bombardment thinning method.The ITO thin film have a small reduction rate of 11.11 nm/min and better electrical conductivity under argon ion beam with a screen voltage of 400V and a beam current of 30mA,Under the existing experimental conditions,the thickness of the surface ITO film is difficult to be precisely controlled during the thinning process,and the surface roughness increases after the ion beam bombardment,which leads to the comprehensive performance of the composite films prepared by the argon ion angle bombardment thinning method are not good for the direct deposition method.