Fabrication and sintering eiiect on the morphologies and conductivity of nano-Ag particle films by the spin coating method

By adjusting the rotating speed and colloidal concentration in the spin coating of silver nanoparticles onto a glass substrate, the coating density could be varied from 1.5 x 10(-6) to 1.1 x 10(-4) g cm(-2), or in other words from a dispersed distribution to multi-layered close packed films. The coating density was found to be proportional to the volume fraction of silver colloids and inversely to the rotating speed to the 0.442 power. The multi-layered films were further investigated for sintering behaviour. Our results indicated that the film started to exhibit a noticeable sintering effect at about 100 degrees C, and at the same time it became electrically conductive. As the treatment temperature increased further, the film resistivity reached a minimum value at 250 degrees C and finally became insulating again when the temperature was over 400 degrees C due to silver coalescence into large particles and breaking up of the conductive paths. Smaller silver nanoparticles, however, would exhibit a similar phenomenon but at lower temperatures.