Hybrid Nanoantenna-Nanopillar Si Schottky Photodetectors for Ultrawide Wavelength-Tunable Photodetection

Active optical antennas, a novel Schottky photodiode design, have drawn significant attention due to their advantages of near-field enhancement and hot-electrons generation for sub-bandgap photodetection. However, the reported active antenna-based Si Schottky photodetectors have shown low photoresponse in a limited wavelength range below 1650 nm. This work reports hybrid nanoantenna (NA)-nanopillar (NP) Si Schottky photodetectors for ultrawide and wavelength-tunable photodetection at room temperature, without using any optical filters. The designed hybrid nanostructure significantly enhances the electric dipole-induced resonance in the NAs, leading to strong and wavelength-tunable light absorption in a wide spectral range from 1200 to 2200 nm. Moreover, due to the strong plasmon resonance and 3D cavity effect in the hybrid nanostructure, room temperature responsivities of 0.46 A W⁻¹ and 0.25 mA W⁻¹, and detectivities of 2.24 × 10¹¹ and 1.25 × 10⁸ cm √Hz W⁻¹ are obtained at 950 and 1700 nm, respectively. The device also features a high response speed of 7.2/7.6 ns (rise time/fall time) and 194/240 µs at 850 and 1310 nm, respectively. Such broadband, wavelength-selective, and high-speed hybrid NA-NP Si Schottky photodetectors, with extended detection wavelength, are promising for Si-based photonic systems for material identification, spectroscopy, imaging, and night vision applications.