Fig. 1 Schematic illustration of the fabrication process of the p-Se film/n-ZnO heterojunction

Fig. 2 SEM images of (a-b) ZnO and (c-d) p-Se/n-ZnO heterojunction (a, c) Top view; (b, d) Cross-sectional view

Fig. 3 (a) XRD pattern of p-Se film and n-ZnO nanorod array, and (b) absorption spectra of pure ZnO and Se/ZnO hybrid structure

Fig. 4 Typical I-V curves for Se-Al2O3-ZnO device under (a) dark, white light and (b) dark, monochromatic lights; I-t curves of the device under (c) dark, white light and (d) dark, monochromatic lights; (e) Long-term response of the device under 500 nm illumination; (f) Spectral responsivity and detectivity of the device at 0 bias voltage

Fig. 5 I-t curves of the Se/Al2O3/ZnO heterojunction device under illumination of (a) 405 nm and (c) 650 nm lasers with varying light intensities (The unit of the light power is mW·cm-2); Relationships between the photocurrent and the light intensity at 0 bias voltage under illumination of (b) 405 and (d) 650 nm lasers

Fig. 6 (a) Diagram of electric circuit to characterize the response speed; (b) Time-dependent voltage curves at different chopper frequency; (c) Normalized voltage-frequency curve; (d) Enlarged one response cycle with rise and decay time

Fig. 7 Energy-band diagrams of the p-Se/Al2O3/n-ZnO nanorod array device (a) before and (b) after contact