A flexible and transparent β-Ga₂O₃ solar-blind ultraviolet photodetector on mica

In the present work, we report a flexible transparent β-Ga₂O₃ solar-blind ultraviolet (UV) photodetector (PD) fabricated on a mica substrate. A laminated a-Ga₂O₃/Ga/a-Ga₂O₃ structure is thermally annealed at 1050 ^◦C, forming a β-Ga₂O₃ film incorporating Ga nanospheres. A PD based on this nanocomposite film has a spectrum response peak at 250 nm, an extremely low dark current of 0.6 pA at a 10 V bias, a very high I_light/I_dark ratio of 3 × 10⁶, and a fast recovery speed of less than 50 ms. Robust flexibility is demonstrated by bending tests and 10 000 cycles of a fatigue test with a radius as small as 8 mm. Compared to a room-temperature-fabricated flexible amorphous Ga₂O₃ (a-Ga₂O₃) PD, the flexible β-Ga₂O₃ PD on mica exhibits improved solar-blind UV photoresponse characteristics. The insertion of a gallium interlayer and treatment by high-temperature post annealing are proposed to contribute to a better stoichiometry and lattice order of the β-Ga₂O₃ thin film, as evidenced by the pronounced Raman peaks related to the Ga_I(O_I)₂ and Ga_IO₄ vibration modes in β-phase Ga₂O₃. Our research is believed to provide a simple and practical route to achieving flexible transparent β-Ga₂O₃ solar-blind UV PDs, as well as other devices such as flexible transparent phototransistors and power rectifiers.