Ultrathin 2D IZO film transistors printed via liquid InZn alloys: insights into the oxidation behavior and enhanced mobility properties

Abstract

Two-dimensional (2D) InZnO (IZO) is a typical and potential transparent conductive oxide for next-generation flexible transparent electronic displays due to its high flexibility, transparency, and high mobility characteristics. In this study, a liquid metal printing method is proposed to prepare atomically thin 2D IZO with controllable composition. Unlike the oxidation process where In dominates the surface oxidation in the liquid In–Sn alloy, the surface oxidation process of the liquid In–Zn alloy is dominated by Zn. Furthermore, the oxidation behavior displays clear characteristics of both competitive and synergistic oxidation. This unique feature allows precise control of the ZnO content in 2D In₂O₃, with Zn content in the film adjustable from 4 at% to 82 at%. Additionally, despite the incorporation of Zn, the film maintains a visible light transmittance of over 99%. As the Zn content in the 2D IZO film increases, the current on/off ratio of the transistor initially decreases and then increases, reaching a maximum of 10⁴, while the field-effect mobility consistently improves. After covering the 2D IZO back channel with 2D Ga₂O₃, a significant enhancement of field-effect mobility is further achieved due to the interface modulation. The findings of this study provide new insights into the oxidation behavior of indium-based liquid alloys and present a novel route for synthesizing 2D IZO thin-film semiconductor materials with varied compositions. This research offers valuable guidance for the development of advanced materials in the field of transparent electronics.