Fig. 1. device structure diagram (a) two-dimensional cross-sectional view, and (b) three-dimensional perspective view：(a) (b)

Fig. 2. surface morphology view of a device etched with microcolumn array under SEM (a) top view, and (b) side view

Fig. 3. surface reflectivity of three devices flat silicon, with microcolumn array etched on the surface and Al₂O₃ grown on the microcolumns

Fig. 4. the I-V curve of the device bias voltage of -5∽5 V and under 808 nm illumination with different intensities (a) the original silicon-based photodetector, (b) the silicon-based photodetector with microcolumn array etched on the surface, and (c) the silicon-based photodetector with Al₂O₃ grown on the microcolumn

Fig. 5. comparison of photocurrent of three devices under 0.1 mW incident light intensity

Fig. 6. comparison of light responsivity of three kinds of devices under the same illumination intensity and bias at 808 nm wavelength