Characteristics of microstructure and electrical resistivity of inkjet-printed nanoparticle silver films annealed under ambient air

The microstructure and electrical resistivity of inkjet-printed silver (Ag) films annealed under ambient air were characterized. Analyses of the impurity amounts in the films using secondary-ion mass spectrometry showed that the decomposition temperature of the capping molecules was just below 170C. Both the characteristics of the microstructure and electrical resistivity when annealed at low temperatures (lower than the decomposition temperature) were significantly different from those when annealed at high temperatures. The results show that neither microstructural features, such as grain size, nor the amounts of impurities can explain both the magnitude and characteristic decrease in electrical resistivity. The changes in electrical resistivity can be described using exponential decay kinetics. The corresponding activation energy of 0.44 eV when annealed at the high temperatures is explained by the migration of point defects such as vacancy-oxygen pairs. On the other hand, negligible dependence on temperature was identified when annealed at low temperatures, which was attributed to decomposition of the capping molecules. The results indicate the importance of controlling the defects of nanoparticles and the properties of capping molecules from the viewpoint of electrical optimization of metallization fabricated using inkjet printing.