Liquid metal printing of 2D IGZO films: Composition control via competitive oxidation and enhanced device performance

In this study, we innovatively fabricated 2D IGZO ultrathin films with several nanometers and tunable compositions using a liquid metal alloy printing method. We systematically studied the relationship between the composition of In-Ga-Zn liquid alloys and the composition of 2D IGZO films and clarified the possible doping mechanism. It was found that the surface film composition was primarily governed by the Gibbs free energy generated from oxide formation. Importantly, Zn and Ga possess a strong and similar competitive oxidation behavior in the oxidation process of liquid InZnGa alloy, leading to the segregation of Ga₂O₃ and ZnO in the oxide skin of InZnGa alloy. In this case, we control the micro doping level of Zn and Ga to realize the composition tailoring of 2D IGZO films. Additionally, this study also reveals that increasing the Zn content in the film reduces the band gap width, increases channel current, and shows a trend where conductivity and carrier mobility increase. In contrast, the increases of Ga content results in an obvious decline of electrical performance for 2D IGZO films. This study demonstrates the superiority of liquid metal printing in the fabrication of two-dimensional materials and optoelectronic devices.