| MgF2 thin film has been used in coverglass of space solar cells because of its low refractive index and high transmittance.But the space environment is complex,optical property of MgF 2 film will be decreased badly bombarded by atomic oxygen and oxygen ions.The application to long-life aircraft in low orbit will be challenged.Besides,uneven charge and discharge phenomena will be happened on the surface of MgF2 thin films because of its insulativity,impacting on the operational performance.Therefore,in this paper,the effects of oxygen ions on optical properties of MgF2 film were studied.The resistance to oxygen corrosion was improved by adding some kinds of oxide on MgF2 film.Furthermore,indium tin oxide(ITO)transparent conducting thin film was deposited on MgF2 thin film.The effects of oxygen ions treatment on optical and electrical properties of ITO film were studied and deeply analyzed in the paper.MgF2 film was deposited by electron beam evaporation and bombarded by oxygen ions beam.The mean transmittance in visible range was decreased by 2%3%,but it can be improved by annealing treatment to some extent.By contrasting erosion rates on PI films of oxygen ions and atomic oxygen,the relation of two kinds of particles was built up.The structures of MgF2 film corroded by oxygen were simulated by TFCale.SiO2 Al2O3 and MgO were chosen to be protective coatings on MgF2 film,and the relevant anti re flection films used to resist oxygen corrosion were designed by TFCale.Among them,SiO2 and Al2O3 were better to be used as anti-corrosion coatings against oxygen.The designed structures were 31nmSiO2/65nmMgF 2/64nm SiO2/glass?13nmSiO2/60nmMgF2/glass?15nmAl2O3/68nmMgF2/58nmAl2O3/glass and 10nmAl2O3/58nmMgF2/glass,and the mean simulated transmittances of them were 93.6%?93.8%.93.9%and 93.70%,respectively,being close to that of MgF2 film.In respect of resistance to oxygen corrosion,the films of 10nmAl2O3/58nmMgF 2/glass had a better performance,and the oxygen corrosion resistance was improved by 40%.Oxygen ions bombardment could improve grain size of ITO thin film.Carrier concentration and mobility were increased,improving the electrical property.The energy gap was increased,leading to the average transmittance in UV range improved by 19.7%.Meanwhile,the mean reflectance in infrared range was enhanced by 19.6%.The mean transmittance in visible range was decreased by 1%because of the increasement of refractive index.Different structures of ITO/MgF2 transparent conducting thin films were designed by TFCale,and then deposited by electron beam evaporation and annealed at 500 ?.Among these,the mean transmittance in visible range of 150nm ITO/100nm MgF2 films was 82.3%,and the square resistance was 79.9?/?,having the best optical and electrical properties.The electrical resistivity by calculation was 1.2 × 10-3 ?·cm.After bombardment by oxygen ions,the mean transmittance in same range was decreased to 71.1%due to the decline of thickness of ITO film.The square resistance was 154?/?,but electrical resistivity by calculation was decreased to about 2.4x10-4?·cm. |
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