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

Abstract 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 Ilight/Idark 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 GaI(OI)2 and GaIO4 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.