Plasmonic Au/Si Microcone Diode Arrays for Superior Photodetection of Near‐Infrared Light

ABSTRACT Plasmonic‐enhanced Schottky photodetector is of great interest for on‐chip silicon photonics thanks to fascinating sub‐bandgap photodetection and high tunability in near‐infrared (NIR) wavelength. Here, a promising Schottky photodetector based on Au/Si microcone diode array is demonstrated for broadband and polarization‐insensitive NIR detection. Particularly, a record high responsivity of 73 mA/W and low noise equivalent power of 2.81 × 10 −14 W·Hz −1/2 at 1.31 µm are achieved at 0 V bias voltage for Au/Si Schottky photodetectors. The photodetector also exhibits a large specific detectivity of 1.66 × 10 11 Jones and a quick response of ∼8 µs. Moreover, it is disclosed that the optimization of microcone size and the reduction of electrode distance can further improve the responsivity. The nanoantenna effects with the abnormal standing‐wave‐like surface plasmon polariton of 3D Au microcone‐shell are unveiled to substantially enhance the absorption of light to generate hot electrons. The unique electric field distribution in Si microcones is also disclosed to arise promising transport paths for efficiently collecting hot electrons. These features promise a superior detector with the capability of broadband and polarization‐insensitive detection, particularly for power‐saving and portable optoelectronic devices. They will substantially advance the development of innovative NIR detectors and promote the integration of optoelectronic systems on silicon platforms.