Effect of RF Power on the Structural, Optical and Electrical Properties of Amorphous InGaZnO Thin Films Prepared by RF Magnetron Sputtering

To investigate the effect of RF power on the structural, optical and electrical properties of amorphous InGaZnO (a-IGZO), its thin films and TFTs were prepared by RF magnetron sputtering method with different RF power conditions of 40, 80 and 120 W at room temperature. In this study, as RF power during the deposition process increases, the RMS roughness of a-IGZO films increased from 0.26 nm to 1.09 nm, while the optical band-gap decreased from 3.28 eV to 3.04 eV. In the case of the electrical characteristics of a-IGZO TFTs, the saturation mobility increased from 7.3 cm(2)/Vs to 17.0 cm(2)/Vs, but the threshold voltage decreased from 5.9 V to 3.9 V with increasing RF power. It is regarded that the increment of RF power increases the carrier concentration of the a-IGZO semiconductor layer due to the higher generation of oxygen vacancies.