Wavelength Modulation and Fast Response of Mixed-Phase β-Ga₂O₃:Zn/SnO₂ in-Plane Heterojunction Ultraviolet Photodetectors

Ultraviolet photodetectors based on wide bandgap mixed-phase β-Ga₂O₃:Zn/SnO₂ thin films formed through doping on the c-sapphire substrate (c-Al₂O₃) are prepared to construct in-plane heterojunctions employing a low-cost and simple preparation method. The mixed-phase thin film photodetectors have a low dark current of 0.74 nA, and the photo-to-dark current ratio ranges from 36.43 to 642.38 at 10 V. The photodetectors also have wavelength modulation, with response peaks ranging from 260 nm (4 mA/W) to 295 nm (1.63 A/W). Furthermore, the photodetectors have a fast response time with a rise time of 0.07 s/0.22 s and a decay time of 0.04 s/0.22 s at 1 V. The excellent performance of the devices is attributed to the reduction of V_O and the establishment of multiple electric fields in the mixed-phase films, which indicates the feasibility of implementing wavelength-modulated and fast-response β-Ga₂O₃ photodetectors using the sol-gel method.