Thermal Stability And Improvement Of Stability For Ag Film In Air

Silver films have been applied widely due to their high reflectance in visible spectral region and low resistivity.However,agglomeration of Ag films inevitably at high temperatures has been considered as a drawback of Ag metallization,which embarrasses their appliations.This dissertation is focused on thermal stability and agglomeration of Ag films at high temperatures in air.The effects of substrate temperature on thermal stability of Ag films have been investigated.For improving the thermal stability,the effects of different intermediate layers on the electrical and optical properties of annealed Ag films also have been studied.The main contents are arranged as follows.Firstly,Ag films were prepared on BK-7 glass substrates by thermal evaporation technique,and subsequently annealed at temperatures between 200 and 400℃in air for 1b.The results show that evolution progress of the structure and morphology of silver films annealed in air is from grains growing,agglomeration to oxidization of surface.Secondly,the influence of the substrate temperatures on the thermal stability of Ag films has been investigated.The results show that the films deposited at higher substrate temperature,the surface of the annealed films is easier oxidization.For the annealed film deposited at high substrate temperature,the agglomeration seems to follow the grain boundary grooving process and size of islands increases with increasing annealing temperature.On the contrary,the annealed film deposited at low substrate temperatrue agglomerates via nucleation of voids followed by the fractal growth of viods.Finally,Al and Cu as the intermediate layers of Ag films have been investigated. Ag/Al,Ag/Cu and Ag/Cu/Al films were prepared,and subsequently annealed in air for 1h at temperatures of 400 and 500℃.Comparing with the pure Ag films,the annealed Ag/Al and Ag/Cu films improve significantly the thermal stability of the films.It is found that in visible region,the reflectance of the annealed Ag/Al is better than that of the annealed Ag/Cu and Ag/Cu/Al film,and the resistivities of annealed Ag/Cu and Ag/Cu /Al films are lower than that of annealed Ag/Al film.