Fig. 1. Schematic of electrode. (a) Top view of electrode; (b) schematic of electrode layered structure

Fig. 2. SEM images of ZnO nanowalls grown at different deposition voltages and EDS spectrum of ZnO nanowalls grown at deposition voltage of 1.6 V. (a) 1.4 V; (b) 1.6 V; (c) 1.8 V; (d) 2.0 V; (e) 2.2 V; (f) EDS spectrum

Fig. 3. XRD patterns of ZnO nanowalls grown at different deposition voltages

Fig. 4. Raman spectra of ZnO nanowalls grown at different deposition voltages

Fig. 5. Photoluminescence spectra of ZnO nanowalls grown at different deposition voltages

Fig. 6. Transmittance spectra of ZnO nanowalls and seed crystal substrate

Fig. 7. Ultraviolet response characteristic diagrams of ZnO nanowalls. (a) UV response curves of ZnO nanowalls; (b) response and recovery curve of ZnO nanowalls at deposition voltage of 1.6 V; (c) UV response and recovery time of ZnO nanowalls versus deposition voltage

Fig. 8. I-V characteristics of ZnO nanowalls. (a) I-V characteristics of ZnO nanowalls at deposition voltage of 1.6 V; (b) photo-to-dark current ratio of ZnO nanowalls versus deposition voltage