Study on the durability against heat in ITO/Ag-alloy/ITO transparent conductive multilayer system

We studied the effects of added metallic elements in Ag-alloy layers of indium-tin-oxide (ITO)/Ag-alloy/ITO transparent conductive multilayer system on the durability against heat. When Ag film was heat treated, agglomeration occurred due to the surface diffusion of the Ag atoms. This caused an increase in the sheet resistance and a decrease in the transmittance. Added metallic elements such as Au, Pd, and Cu in Ag-alloy layers increased the onset temperature and activation energy for agglomeration. These added metallic elements also decreased the surface energy of the Ag film. The durability against heat was improved by adding metallic elements to the Ag film of the ITO/Ag/ITO multilayer system. Cu atoms, especially, diffused out to the surface of the Ag film hindered the surface diffusion of the Ag atoms, resulting the improvement of thermal stability of the Ag film. The figure of merit (FOM, T-10/R-square) of ITO/Ag/ITO multilayer decreased to 1/15 of its initial value after heat treatment at 450 degrees C for 6 h, whereas it decreased to 1/3 of its initial value when Pd and Cu were added to Ag film. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim