X-ray diffraction patterns of the IZTO films deposited onto glass substrates at room temperature by RF magnetron sputtering are shown in Figure 1. The amorphous nature is clearly seen in all samples. This commonly happens in many multicomponent complex mixed oxide films where the crystallization energy is considerably higher than the thermal energy available at room temperature. Similar results were reported elsewhere , where IZTO films with low zinc content deposited at room temperature remained in amorphous state . The crystallinity of the films is known to be affected by the processing variables, such as gas ambient, deposition temperature, working pressure, annealing temperature, and chemical composition . However, even after annealing with temperature of up to 350 °C, no particular diffraction peaks corresponding to crystalline phases were observed from all IZTO films we had prepared. Furthermore, the surface topography observed using AFM revealed that subsequently, all films showed very smooth and uniform surface, which is very important for TFT application to minimize defects at the interlayers . There was no prominent change in root-mean-square surface roughness values (Rq), which increased from about 0.2 nm to 0.3 nm for all IZTO films as the annealing temperature increased, as summarized in Table 1.