van der Waals epitaxy of flexible κ -Ga2O3 thin films on mica for low-power near-linear solar-blind ultraviolet photodetection

Flexible solar-blind ultraviolet (UV) photodetectors based on ultrawide-bandgap Ga2O3 are attractive for wearable sensing and conformal optical monitoring, yet achieving high crystallinity and a linear photoresponse in metastable κ-Ga2O3 on flexible substrates remains challenging. Here, a highly [001]-oriented κ-Ga2O3 thin film is grown on flexible mica by van der Waals pulsed laser deposition and integrated into a solar-blind UV photoconductor. The κ-Ga2O3 (002) ω-rocking curve exhibits a narrow full width at half maximum of 0.108°. Consequently, at 10 V, the device delivers a low dark current of 8.6 × 10−11 A, a photo-to-dark current ratio of 5169, and a near-linear photocurrent dependence over 1–1600 μW/cm2 under 254 nm illumination with a power-law exponent of 0.968. Moreover, the detector maintains stable operation across bending radii of 8–12.5 mm and retains 97.8% of its initial photocurrent after 2000 bending cycles at an 8 mm radius, while post-bending x-ray diffraction confirms κ-phase retention. These results establish κ-Ga2O3/mica as a reliable platform for conformal deep-UV sensing.