Performance of plamson induced hot electrons-based photodetectors largely relies on the photon absorption capability. To improve the optical absorption, many perfect absorbers based on the periodic metallic nanostructures have been designed and fabricated through low-throughput, costly and time-consuming lithographic processes, which seriously limit the future potential applications of plasmonic hot electrons optoelectronics devices. Here, a large-scale, broadband absorber consisting of ITO film, ZnO layer, Au film and Al nanospike array substrate was designed and fabricated for hot electrons-based photodetection. The new designed absorber’s absorptivity can be up to 70% in the broad wavelength range from 400 nm to 800 nm (even up to 90% in the wavelength range from 400–550 nm) and most of the absorption comes from the Au film, which is effective for the generation of hot electrons. The enhanced broadband absorption is ascribed to the surface plasmon polariton mode and localized surface plasmon resonance mode supported by the nanospike arrays. The influence of geometry and material parameters on the optical absorption properties is also specifically investigated through numerical simulation. The efficient and broadband absorption of a nanospikes device results in a much larger photocurrent compared with that of a planar reference device. Our approach, which is compatible with large-scale manufacturing, paves the way for the practical implementation of hot electrons-based optoelectronic devices.

Hot electron can break through the native limitation of silicon energy gap and expand its photo-response range. Plasmon modes improve detectors responsivity by the high hot electrons production. In this letter, we designed a C-shaped groove array carved on gold/silicon substrate, and numerically studied its optical properties and hot electron responsivity. An especial electromagnetic resonance (the dipole toroidal mode) can be excited in this nanostructure, which brings a nearly perfect absorption (∼98%) at 1395 nm and a higher responsivity. Our simple design demonstrated an effective hot electron photodetector without extra collect electrodes.