| AVS 66th International Symposium & Exhibition | |
| Fundamental Aspects of Material Degradation Focus Topic | Thursday Sessions |
| Session DM+BI+SS-ThM |
| Session: | Material Stabilities and Technology for Degradation Protection |
| Presenter: | Midori Kawamura, Kitami Institute of Technology, Japan |
| Authors: | M. Kawamura, Kitami Institute of Technology, Japan E. Kudo, Kitami Institute of Technology, Japan Y. Sasaki, Kitami Institute of Technology, Japan T. Kiba, Kitami Institute of Technology, Japan Y. Abe, Kitami Institute of Technology, Japan K.H. Kim, Kitami Institute of Technology, Japan H. Murotani, Tokai University, Japan |
| Correspondent: | Click to Email |
Silver (Ag) thin films possess high electrical and optical properties, but their low stability should be resolved. We have developed a highly stable Ag thin film where thermal agglomeration can be suppressed, by utilizing nanometer thick surface Al layers. Then we have confirmed that Al surface nanolayer deposited Ag films show a high optical reflectance as well as Ag single film. Here, the Al nanolayer was oxidized to be Al oxide nanolayer, being transparent in visible region, by natural oxidation in air. In the present study, we investigate durability of the Ag films with surface nanolayers under high humidity condition.
We prepared Ag single layer (150 nm), Ti (1, 3 -nm) / Ag films and Al (1, 3 -nm) / Ag films on glass substrate by rf magnetron sputtering in Ar discharge. In addition, vacuum evaporation method was also used for the preparation of Al (1, 3 -nm) / Ag films. A difference on degradation of the films by different fabrication methods was investigated. The samples were kept for 16 hrs in a chamber where temperature and humidity was set to 55oC and 90%RH, respectively.
After the test, agglomeration occurred in Ag single layer and optical reflectance was decreased. On the other hand, Ti or Al nanolayer covered Ag films kept smooth surface even after the test. The surface roughness observed using AFM was as small as 1.0 nm. As a result, we have found that both Al and Ti surface nanolayers can play significant role as protective layer under high humidity condition. However, Ti / Ag films showed a lower reflectance due to light absorption by TiO2 layer formed on the surface, and the samples with Al surface nanolayer showed a higher optical reflectance.
By XPS analysis, very thin Ag sulfide formation was observed in Ag single film after the humidity test, but not in Ti or Al covered Ag films. This suggests very thin Al oxide or Ti oxide nanolayer prevented contact of Ag atoms and SO2 gas in air. However, Ag signal was detected in the surface oxide layers, which indicates onset of outward diffusion of Ag atoms.