Effects of Annealing Temperature on the Properties of Ga-doped In₂O₃ Thin Films

Ga-doped In2O3 (GIO) thin films were deposited on glass substrates at a growth temperature of 300 ◦C by using radio-frequency magnetron sputtering. The deposited films were then subjected to rapid thermal annealing (RTA) at various temperatures. The annealed films were characterized by using X-ray diffraction (XRD), ultraviolet-visible spectrophotometry, scanning electron microscopy, and Hall-effect measurements. The optical bandgap, electrical resistivity, and figure of merit of the GIO thin films were found to depend significantly on the RTA temperature. The XRD patterns of the films indicated that all the films had a body-centered cubic structure, with the primary peak being the (222) diffraction peak. The average optical transmittance of the GIO thin films for wavelengths of 500 − 1100 nm increased from 44.5% before annealing to 87.2% after annealing at 450 ◦C; the figure of merit was also the highest after annealing at this temperature. These results indicate that the properties of GIO thin films can be varied by controlling the RTA temperature.