Annealing Effects on Opto-electronic Properties of Thermally-evaporated ITO/Ag/ITO Multilayered Films for Use in Color Filter Electrodes

The effects of post-deposition annealing on optical and electrical properties of thermallyevaporated ITO/Ag/ITO films have been investigated. The thickness of ITO, Ag and ITO films in the multilayered structure was constant at 50, 10 and 40 nm. The multilayered films were deposited on glass substrate without intentional substrate heating. A significant variation in resistivity and transparency was observed after thermal treatment from 300 to 540°C for 1 h. The high-quality films with resistivity as low as 3.5×10 Ohm-cm and transmittance more than 70% have been obtained by using suitably-controlled deposition parameters. The films grain structures and the surface morphology were illustrated using the X-ray Diffraction Patterns (XRD) and Scanning Electron Microscopy (SEM) respectively. The allowed direct band gap at the annealing temperature ranging from 300-540°C was estimated to be in the range of 3.62-3.78 eV. A band gap widening with an increase in annealing temperature was observed.