The electrical and optical properties of thin layers of nano-sized antimony doped tinoxide particles

For the use in anti-static films on glass or polymeric substrates, transparent conductive layers can be prepared by spinning an aqueous suspension of nano-sized antimony-doped tinoxide (ATO) particles. These layers have a resistivity which is substantially higher than that of homogeneous ATO layers which are deposited by physical vapour deposition techniques. By curing the films to temperatures up to 700 degrees C, the resistivity of the particle layer can be decreased by two or three decades. Because the nano-sized particles are prepared by a low-temperature process a different mechanism can contribute to this decrease in resistivity. Possible effects which may influence the conductivity are sintering of the particles, change of the bulk material and the presence of an insulating layer at the outside of the particles. This decrease can be explained by the presence of an insulating antimony-rich layer on the outside of the particles, the thickness of which is reduced when the layer is cured. At temperatures above 350 degrees C, sintering of the particles also highly influences the decrease in resistivity. At temperatures above 700 degrees C, the resistivity is increased due to segregation of the antimony to the surface of the particle. (C) 1999 Kluwer Academic Publishers.