Preparation And Optimal Design Of ITO Films

As a unique photoelectric functional material, transparent conductive film (ITO) concurrently have both high visible transmission and well conductivity. And so, it's accepted by people. It is the excellent photoelectric characteristics that it's widely used in solar battery, gas sensors, LCD display, etc. As relative areas in the photoelectric conversion, luminous brightness.etc request further research and development, more stringent requirements are asked on the system components (including ITO). For example, as reflex face of a new display device OLED and transparent anode material, ITO layers have a direct relation with the property of OLED device. In addition to a high standard of optical performance, roughness aspect plays a key role and should be strictly controlled on the ITO to OLED.To prepare the high quality ITO films, there are two steps to finish the goal in this paper:the first, optimize a few of important parameters which have effect on ITO films:ratio of oxygen and argon, sputtering pressure, temperature, and power; and then obtain the optimum preparation conditions; the second, under the optimum conditions, use energy-filtered magnetron sputtering (EFDMS) of independent development in our lab to further study. Main conclusions in this paper follow:Several technological parameters such as ratio of oxygen and argon, sputtering pressure, temperature, and power had been optimized, and the optimum parameters of prepare transparent and conductive ITO films had been obtained as following.Under the condition of keeping the argon flow of 44 sccm and the oxygen flow is about 0.6sccm, transmissivity of the films can reach above 85%and lower resistivity can be achieved, and the ITO films prepared have stronger diffraction peak. During the 0.7-0.9 pa sputtering pressure, the ITO films prepared have better transmissivity, conductivity. With the condition of 75℃-375℃chosen, photoelectric property of ITO films prepared at 375℃is best. By SEM, ITO films prepared at 375℃have more ordered crystal structure and flat surface except pits and somewhat defects in grain boundaries. Power provides energy to deposition grains so as to promote grain to grow, but suffer inhibition from other grains and substrate in the parallel direction, and at last the gains exhibit columnar growth, form peaks and then enlarge the surface roughness. So, power should be reduced in order to prepare ITO thin film with high performance and low roughness as far as possible.More superior ITO transparency conductive films can be prepared by adopting EFDMS technology. To optimize the size of mesh that has direct relation with preparing the ITO films, it is obtained that ITO films prepared in 600 meshes possess fine crystal grain and flat surface. Nevertheless, EFDMS technology reduces the deposition rate. So, EFDMS technology based on conventional magnetron sputtering (DMS) technology is utilized to coat the second layer ITO film to get double layers ITO films. Hence, it could improve roughness and deposition rate of ITO films, meanwhile do not affect photoelectric property of films, which could spare the target materials. In the experiment, three groups including 90+20,95+15, and 100+10(nm), and film topography, grain size, photoelectric property of ITO films prepared by DMS and EFDMS technology have been compared. The results show:when keeping the sum thickness of 110nm stable, thickness of 20 nm by EFDMS technology, that is 90+20 group, roughness of double layer ITO films can reduce to 1.259nm, and its optical transmittance reach 90%, resistivity only has 2.454 x 10-4Ω·cm.