van der Waals Lamination for Effective Bottom Channel Modulation of Oxide Transistors

Plasma treatment has been widely used to improve the performance of oxide transistors. However, the real active channel of the back-gated transistors is typically buried close to the dielectric interface and cannot be effectively modulated by plasmas. In this work, we report a bottom plasma treatment strategy that can directly modulate the oxide channel. Within this process, the as-deposited oxide channel could be physically peeled off from the sacrificial wafer using the van der Waals delamination process, exposing the bottom channel region for direct plasma treatment. After treatment, indium gallium zinc oxide (IGZO) transistors exhibit a large on-off ratio of 4 × 10⁸ and high carrier mobility over 25 cm² V^-1 s^-1, which is over 4 times higher compared to the control device with conventional top plasma treatment. Furthermore, detailed X-ray photoelectron spectroscopy measurements confirm that the improved performance originates from the passivation of oxygen vacancy and nitrogen doping within the active bottom channel region.