Low Temperature Ito Film Preparation And Performance

Organic light-emitting diodes(OLED) is a hot topic in display field. Because of better conductivity, higher transparency, smoother surface and higher work function, ITO (Indium tin oxide) films are used as the transparent electrodes which are the emitting side in OLED. ITO films with low sheet resistance can be obtained by raising the substrate temperature during deposition or annealing in the inert gases at high temperature. However, it is necessary to deposit ITO films at low substrate temperature because some displays can't endure the high temperature which will damage the materials such as flexible substrates, organic inject materials, thin film transistors (TFT) of OLED devices, and so on. To meet the demands of transparent electrodes of OLED devices, ITO films were deposited at low substrate temperature, and their performances were discussed in this paper.Firstly, ITO films were produced by DC magnetron sputtering at low substrate temperature which was lower than 200℃. In order to increase the conductivity and transparency of ITO films, little vapor was injected into argon and oxygen gas atmosphere. The alterable sputter parameters including deposition pressure, oxygen flow, vapor partial pressure, DC power and substrate temperature were initialized by orthotropic experiment. From the optimization experiment, it was concluded that, the best parameters of sputtering ITO films were deposition pressure of 1mTorr, O2 flow of 0sccm, vapor partial pressure of 2×10-5Torr, DC power of 200W, substrate temperature of 100℃. The figure of merit of ITO film deposited under these conditions was 3.10×10-3S, the sheet resistance was 53.8?/□and the mean transmittance in visible region was 83.6% when the thickness of ITO film was 10nm. In this paper, the figure of merit of film was firstly used to select the sputtering parameters of ITO films. It was proved that this way was feasible. It was emphatically discussed that the dependence of the uniformity, structure, surface morphology, conductivity and transparency of ITO films on vapor partial pressure.The multilayer films instead of the single ITO films were deposited to reduce the sheet resistance of films. The multilayer structure consisted of tree layers, ITO/Ag/ITO.