Fig. 1. (a) Schematic diagram of the proposed HEPD based on Au/TiO₂ composite nanostructure; (b) Structural diagram of the energy levels of the materials used in the proposed HEPD; (c), (d) Cross-sectional and top-view SEM images of the proposed device respectively

Fig. 2. (a) I-V curves of devices with different thicknesses of TiO₂ film (t_TiO²) in the dark state. The response characteristics of the device witht_TiO²= 20 nm under 0 V bias: (b) Absorption spectra; (c) External quantum efficiency (EQE); (d) Responsivity; (e) Linear dynamic range. (f) Schematic diagram of hot electron generation and transfer process over the Au/TiO₂ Schottky barrier

Fig. 2. [in Chinese]

Fig. 3. The rise and fall response speeds of the device under 0 V bias: (a) Under the illumination wavelength of 850 nm; (b) Under the illumination wavelength range varying from 375 nm to 850 nm

Fig. 4. Comparison of response performance of devices with different t_TiO² andt_Au respectively: (a), (c) Transient photocurrents; (b), (d) Photocurrents and the corresponding average light absorption efficiencies

Fig. 5. (a) Comparison of the transient photocurrents for the devices with different t_n-Au; (b) Comparison diagram between the photocurrents and average absorption efficiencies of the devices with different t_n-Au. The normalized electric field distributions (|E|²): (c) The optimal device with t_n-Au = 4 nm and (d) the reference device

Fig. 6. Comparison of response performance of devices with top conformal metal films of Au-film, Ag-film and Cu-film: (a) Transient photocurrents; (b) Photocurrents and the corresponding average light absorption efficiencies