Photoluminescence and Electrical Properties of IGZO Thin Films Prepared by Sputtering and Solution Processes

Indium-gallium-zinc-oxide (IGZO) is a semiconducting oxide material with high carrier mobility, and utilized as a thin film transistor. There are two methods normally used to fabricate the IGZO thin films; sputtering and solution techniques. For sputtering technique, the powder mixture of indium oxide (In₂O₃), gallium oxide (Ga₂O₃) and zinc oxide (ZnO) were grinded and pressed then heat at 1300 °C for 3 hours. The x-rays diffraction pattern of the sintered IGZO disc indicates the crystal structure of IGZO compound. The IGZO disc with a diameter of 3 inches was employed for the target of radio frequency (RF) magneton sputtering (13.56 MHz). The IGZO thin film was prepared on the glass or quartz substates under Ar atmospheric pressure of 5 x 10^-3 mbar at RF power of 60 W for 30 minutes. In addition, the ease fabrication technique of solution process was also conducted to prepare IGZO thin films from the solution mixture of metal precursors dissolved in 2-methoxyethanol at 75 °C for 12 hours to form a partial network of metal-oxygen-metal bonds. Subsequently, the deep ultraviolet was irradiated under nitrogen gas for 2 hours. The high carrier mobility of 0.5 and 10.9 cm²/Vs can be achieved for IGZO thin films prepared from sol-gel and sputtering methods, respectively. The photoluminescence excitation was proposed to examine the defect levels in both prepared films, and these spectra can be used to relate to the electric properties of the prepared IGZO films.