Investigation of Ga and F co-doping effects on the electrical, optical, and structural properties of ZnO thin films for transparent electrode applications

Co-doping is a widely employed strategy for enhancing the electrical properties of ZnO thin films. In this study, Gallium (Ga) and Fluorine (F) were simultaneously incorporated into transparent conductive ZnO (F_xGa_y_ZnO) via the DC magnetron sputtering technique. This research not only identifies the optimal co-doping ratios of F and Ga but also elucidates the critical role of Ga in providing a substantial concentration of electron carriers. Concurrently, F is shown to effectively passivate oxygen vacancies, thereby enhancing the electron mobility of pure ZnO thin films. The results indicate that an 800 nm thickness ZnO film with an optimal doping composition of 3% atomic Ga and 1% atomic F (designated as FGZO), deposited on a glass substrate at 500 °C in an Argon atmosphere, achieves remarkable metrics: a carrier concentration of 6.33 × 10²⁰ cm⁻³, electron mobility of 40.59 cm²/V.s, and a resistivity of 2.7 × 10⁻⁴ Ωcm. This doping ratio represents the most effective configuration explored in this study. Furthermore, the average transmittance in the visible and near-infrared regions exceeds 80%. The FGZO thin film exhibits considerable potential for various applications as transparent electrodes in optoelectronic devices.