Achieving Infrared Detection by All-Si Plasmonic Hot-Electron Detectors with High Detectivity.

An improved architecture for all-Si based photoelectronic detectors has been developed, consisting of a specially designed metasurface as the antenna integrated into a Si nanowire array on the insulator by an electron beam lithography based self-alignment process. Simulation using the Finite Difference Time Domain (FDTD) method was carried out to ensure perfect absorption of light by the detector. Optic measurement shows a 90% absorption at 1.05 μm. Photoelectronic characterization demonstrates the responsivity and detectivity as high as 94.5 mA/W and 4.38 × 1011 cm Hz1/2/W, respectively, at 1.15 μm with the bandwidth of 480 nm, which is comparable to that of III-V/II-VI compound detectors. It is understood that the outstanding performances over other reported all-Si based detectors originate from the enhanced quantum efficiency in one-dimensional conduction channels with high density of states, which efficiently accommodate the emitted plasmonic hot electrons for high conduction in the Si nanowires, enabling the near-infrared detection by all-Si based detectors.