Electrical and Optical Characterization of Indium Tin Oxide (ITO) Films for Low Resistance Transparent Electrode
One of obstacles hindering a realization of large area size twisted nematic liquid crystal display (TN-LCD) flat panel (for example, 1100 x 1250 mm) is a slow response time. The slow response time is due to the inverse proportionality of turn on time with the frame frequency and pixel number (number of gate lines) in the twisted nematic liquid crystal system. It is known that the slow response time in the active matrix system of LCD be solved by reducing the sheet resistance of color filter electrodes. In this paper, we report on the processing details of the deposition of transparent ITO films using a DC sputtering system. The thickness of ITO layer was set for high transmittance and good conductivity and the films were characterized with respect to the transmittance and sheet resistance. The deposited ITO films show a good uniformity across the whole area and the average thickness of the ITO is about 1350 Å under the DC power of 10.7 kW. The transmittance is increased from 72.5 to about 93 % as the oxygen content is increased to 2.5 sccm for the samples without annealing. It was found that the transmittance is significantly improved by the annealing process at 220 oC for 40 min. up to 94 %. The sheet resistance is decreased with the DC power and exhibits below 22 / after the samples were annealed.
S.-G. Kang and T. Kobayashi
D. H. Yoo and M. W. Shin, "Electrical and Optical Characterization of Indium Tin Oxide (ITO) Films for Low Resistance Transparent Electrode", Materials Science Forum, Vols. 449-452, pp. 1001-1004, 2004