Squeeze-Printing Ultrathin 2D Gallium Oxide out of Liquid Metal for Forming-Free Neuromorphic Memristors

Two-dimensional (2D) metal oxides exhibit extraordinary mechanical and electronic properties, leading to new paradigms in the design of electronic and optical systems. However, as a representative, a 2D Ga₂O₃-based memristor has rarely been touched, which is hindered by challenges associated with large-scale material synthesis. In this work, the ultrathin 2D Ga₂O₃ layer (∼3 nm thick) formation on the liquid gallium (Ga) surface is transferred with lateral dimensions over several centimeters on a substrate via the squeeze-printing strategy. 2D Ga₂O₃-based memristors exhibit forming-free and bipolar switching behaviors, which also reveal essential functions of biological synapse, including paired-pulse facilitation, spiking timing-dependent plasticity, and long-term depression and potentiation. These results demonstrate the potential of 2D Ga₂O₃ material for neuromorphic computing and open up an avenue for future electronics application, such as deep UV photodetectors, multimode nanoresonators, and power switching devices.