Freestanding Crystalline β-Ga₂O₃ Flexible Membrane Obtained via Lattice Epitaxy Engineering for High-Performance Optoelectronic Device

Wearable and flexible β-Ga 2 O 3 -based semiconductor devices have attracted considerable attention, due to their outstanding performance and potential application in real-time optoelectronic monitoring and sensing. However, the unavailability of high-quality crystalline and flexible β-Ga 2 O 3 membranes limits the fabrication of relevant devices. Here, through lattice epitaxy engineering together with the freestanding method, we demonstrate the preparation of a robust bending-resistant and crystalline β-Ga 2 O 3 (−201) membrane. Based on this, we fabricate a flexible β-Ga 2 O 3 photodetector device that shows comparable performance in photocurrent responsivity and spectral selectivity to conventional rigid β-Ga 2 O 3 film-based devices. Moreover, based on the transferred β-Ga 2 O 3 membrane on a silicon wafer, the PEDOT:PSS/β-Ga 2 O 3 p–n heterojunction device with self-powered characteristic was constructed, further demonstrating its superior heterogeneous integration ability with other functional materials. Our results not only demonstrate the feasibility of obtaining a high-quality crystalline and flexible β-Ga 2 O 3 membrane for an integrated device but also provide a pathway to realize flexible optical and electronic applications for other semiconducting materials.