Transferable Ga2O3 Membrane\nfor Vertical and Flexible Electronics via One-Step Exfoliation

Transferable Ga2O3 thin film membrane\nis\ndesirable for vertical and flexible solar-blind photonics and high-power\nelectronics applications. However, Ga2O3 epitaxially\ngrown on rigid substrates such as sapphire, Si, and SiC hinders its\nexfoliation due to the strong covalent bond between Ga2O3 and substrates, determining its lateral device configuration\nand also hardly reaching the ever-increasing demand for wearable and\nfoldable applications. Mica substrate, which has an atomic-level flat\nsurface and high-temperature tolerance, could be a good candidate\nfor the van der Waals (vdW) epitaxy of crystalline Ga2O3 membrane. Beyond that, benefiting from the weak vdW bond\nbetween Ga2O3 and mica substrate, in this work,\nthe Ga2O3 membrane is exfoliated and transferred\nto arbitrary flexible and adhesive tape, allowing for the vertical\nand flexible electronic configuration. This straightforward exfoliation\nmethod is verified to be consistent and reproducible by the transfer\nand characterization of thick (∼380 nm)/thin (∼95 nm)\nκ-phase Ga2O3 and conductive n-type β-Ga2O3. Vertical photodetectors are fabricated based\non the exfoliated Ga2O3 membrane, denoting the\npeak response at ∼250 nm. Through the integration of Ti/Au\nOhmic contact and Ni/Ag Schottky contact electrode, the vertical photodetector\nexhibits self-powered photodetection behavior with a responsivity\nof 17 mA/W under zero bias. The vdW-bond-assisted exfoliation of the\nGa2O3 membrane demonstrated here could provide\nenormous opportunities in the pursuit of vertical and flexible Ga2O3 electronics.