Fig. 1. Preparation process of porous Ga₂O₃/GaN heterojunction photodetector

Fig. 2. SEM images of porous GaN films and porous Ga₂O₃/GaN heterojunctions. (a) SEM image of top view of porous GaN film etched in NaCl solution; (b) SEM image of top view of porous GaN film etched in NaNO₃ solution; (c) SEM image of top view of porous GaN film etched in NaOH solution; (d) SEM image of top view of S0 heterojunction; (e) SEM image of top view of S1 heterojunction; (f) SEM image of top view of S2 heterojunction; (g)‒(i) cross-sectional SEM views corresponding to above heterojunctions

Fig. 3. XRD patterns and room temperature Raman spectra of porous Ga₂O₃/GaN heterojunctions. (a) XRD patterns; (b) room temperature Raman spectra

Fig. 4. Optical properties of porous Ga₂O₃/GaN heterojunctions. (a) Ultraviolet absorption spectra; (b) curves of (Ahv)²-hv

Fig. 5. Schematic diagram of thermal oxidation of porous GaN film

Fig. 6. I-V curves of porous Ga₂O₃/GaN heterojunction photodetectors. (a) S0 (insert is diagram of device); (b) S1; (c) S2

Fig. 7. I-t curves of porous Ga₂O₃/GaN heterojunction photodetectors under 254 nm and 365 nm illumination. (a)‒(c) I-t curves of S0, S1, and S2 heterojunction photodetectors under 254 nm illumination; (d)‒(f) I-t curves of S0, S1, and S2 heterojunction photodetectors under 365 nm illumination

Fig. 8. Energy bands and carrier transport mechanisms of Ga₂O₃/GaN heterojunction under 254 nm and 365 nm illumination. (a) 254 nm; (b) 365 nm