Fig. 1. Structural diagram of ZnO ultraviolet photodetector

Fig. 2. Performance characterization of ZnO film. (a) XRD spectra of ZnO film and Al₂O₃; (b) UV-visible absorption spectrum of ZnO film with (αhν)²-hν spectrum shown in inset

Fig. 3. Performance characterization of ZnO ultraviolet photodetector. (a) SEM image of ZnO ultraviolet photodetector with MSM structure; (b) cross-sectional SEM image of device; (c) top view of SEM image of ZnO film; (d) top view of SEM image of Au film

Fig. 4. I-V characteristic curves in logarithmic coordinate

Fig. 5. Spectral responsivity curves of ZnO ultraviolet photodetector.(a) Responsivity of ZnO ultraviolet photodetector with different external bias voltages; (b) peak responsivity versus external bias voltage; (c) normalized responsivity of ZnO ultraviolet photodetector; (d) enlarged diagram of response cutoff wavelength with response cutoff wavelength versus bias voltage shown in inset

Fig. 6. Schematic of semiconductor electron energy band. (a) Semiconductor energy band diagram; (b) energy band tilt diagram under action of electrical field