Liquid-metal-assisted exfoliation of 2D β-Ga2O3 with high anisotropy ratio for solar-blind detection and polarization imaging

Solar-blind UV polarization detection and imaging can reflect more detailed optical information, which is vital for developing next-generation deep UV optoelectronic devices. β-Ga2O3 with ultra-wide bandgap is an ideal candidate for solar-blind UV detection application. However, the bulky nature of Ga2O3 limits its application in miniaturized, integrated and multifunctional devices, and polarization imaging based on Ga2O3 photodetector has not yet been realized. Here, we report a convenient method to prepare 2D β-Ga2O3 flakes via liquid-metal-assisted exfoliation. Benefiting from high crystallinity and polarization-sensitive absorption of prepared ultrathin β-Ga2O3 flake in monoclinic structure, the β-Ga2O3 photodetector exhibits an ultra-fast response speed (100/78 μs for rise/decay time) and a prominent anisotropy ratio (∼2.8) of polarization photoresponse under 265 nm illumination. An unambiguous detection of linearly polarized light has also been realized by the double symmetry-breaking of twisted β-Ga2O3 photodetectors. Moreover, a four-layer twistedly stacked detection system further enables a one-step and well-defined polarization imaging with high resolution (150 × 150 pixels) to acquire spatial polarization information. This work presents a novel strategy for preparing ultrathin 2D gallium oxides and demonstrates a promising route to realize well-defined solar-blind polarization imaging in a simple manner.