Tin-doped indium oxide(ITO)thin films were deposited on quartz glass and corning glass #1737 substrates by D.C. reactive magnetron sputtering using an In-10wt%Sn alloy target. Oxygen was introduced near the substrate in order to reduce oxidation of target. Argon was done near the target. The films were deposited in the oxygen flow ratio from 8% to 16% and in the temperature from 100℃ to 200℃.
The resistivity was little variation over 150℃. It was the lowest at the point of 12% oxygen flow ratio. The transmittance was kept over 85% beyond 12% oxygen flow ratio. Hall effect measurement and micro-structural analysis were done to understand the variation of the sheet resistance. It was found that carrier mobility is a dominant factor for controlling the sheet resistance more than the carrier concentration in the optimum range.
The intrinsic stress and the orientation with oxygen flow ratio at the optimum substrate temperature(150℃) were analyzed by X-ray diffraction method. Intrinsic stress was the highest compressive stress in the optimum point(12% in the oxygen flow ratio). It was explained by micro-structure and reflected neutral flow ratio. Preferred orientation was (111). It was explained from the surface and strain energy calculation of the film. (111) orientation has lower strain energy plane than (100) and (110).
GIXR(grazing incidence X-ray reflectivity)method was used to investigate the effect of the density at 150℃. The density was the highest in the optimum point with oxygen flow ratio.
To relax compressive stress, the films were holded for 30min in the vacuum after deposition in the 150℃. Intrinsic stress of ITO thin films changed from compre-ssive stress to zero stress. Preferred orientation varied from (222) to (400) to reduce the strain energy. The density remained the highest value while the resistivity showed little change in the optimum point.
In this study, it was found that the resistivity of the ITO thin films depended on film density not film orientation and stress.
