Highly sensitive and ultrafast deep UV photodetector based on a β-Ga₂O₃ nanowire network grown by CVD

We investigated a high-performance deep ultraviolet photodetector based on a β-gallium oxide (β-Ga₂O₃) nanowire network. β-Ga₂O₃ nanowires were grown at different temperatures by a chemical vapor deposition method. X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive spectrum analysis were utilized to characterize the structure and morphology. With increasing the temperature, the nanowires became thicker and their surface appeared more rough with many kinks and branch-like shapes. It is proposed that the growth mechanism is dominated by a combination of vapor-liquid-solid and vapor-solid growth. A photodetector based on the best quality β-Ga₂O₃ nanowire network was fabricated by a simple and cheap mask method, which exhibited excellent photoelectric performance. The responsive spectrum presented a peak response located at 231 nm with a sharp cutoff at 270 nm. The response rejection ratio of I _{231 nm}/I _{290 nm} is more than three orders of magnitude, demonstrating an intrinsic solar-blindness. The full width at half maximum of the response curve is only 1.2 ns under pulsed laser irradiation. The high sensitivity, superior selectivity, ultrafast response speed and simple fabrication technology show that the β-Ga₂O₃ nanowire network has promising application in solar-blind photodetectors.