Ultra-flat ITO films on mica for high temperature transparent flexible electrodes

Indium tin oxide (ITO) films were deposited on transparent and flexible mica substrates by RF magnetron sputtering at room temperature. The ITO films exhibit atomically flat morphology on the cleaved natural mica surface. Excellent thermal stability of mica allows heat treatment at high temperature up to 500 degrees C. The electronic and optical characteristics of the ITO films are improved by annealing process, which can be explained by the preferred (2 2 2)-oriented crystallization at temperatures higher than 200 degrees C. The resistivity of as-deposited amorphous ITO film is similar to 2.1 x 10(-3) Omega cm and remarkably decrease to similar to 5.0 x 10(-4) Omega cm for the annealed samples. Accompanying the rapid increase in the conductivity, the transmittance also increases to more than 90% for the crystallized ITO films. Furthermore, the mechanical tests indicate excellent flexibility and durability of the ITO films on mica. These results demonstrate that the ITO films on mica can endure high temperature process for the applications in flexible electronics.