Enhanced structural and optoelectronic characteristics on Gallium-doped ZnO thin film by Intermittent process

In this study, the called “Intermittent Process” is designed to enhance structural and optoelectronic properties of Gallium-doped ZnO (GZO) thin film, which is defined as discontinuously thin film growth process by inserting the intermittent time to form multiple layers. Therefore, there are two main parameters are included, which are Intermittent Number (IN) and Intermittent Time (IT). In this study, the different intermittent numbers (IN) as 0, 1, 2, 3, 4 and the various intermittent time (IT) as 5, 7.5, 10, 12.5, 15 min had been chosen. After the optimum IN and IT are studied, the substrate heating will also be treated to improve the quality of thin film during intermittent process, which includes 300 °C, 400 °C, 500 °C. The structural property of thin films was analyzed by X-ray diffraction (XRD), the surface morphology was observed by using field emission scanning electron microscope (FE-SEM). The resistivity and transmittance were measured by Hall characteristic measurement system and UV-VIS-NIR spectrophotometer, respectively. Atomic resolution microstructures are observed by high resolution transmission electronic microscopy (HRTEM). The result shows that the thin film has the optimum quality when the IN = 2 and IT = 12.5 min during 400 °C substrate heating, which means the resistance reduces to 6.1 × 10−3Ω-cm, and the average transmittance in visible region increases to 84.20%. The optimum figure of merit (FOM) is calculated as 2.35 × 10−4Ω−1. In this study, the designed ‘intermittent process’ is verified to effectively enhance the structural and optoelectronic properties of GZO thin film.