Abstract

Plasmon nanostructures and metasurfaces have been intensely studied and applied in different applications, such as sensing, beam shaping, super-resolution imaging, energy harvesting, photocatalysis, and photodetection because they enable strong light absorption and scattering, and near-field amplification [1-3]. This work is focused on the development of low-cost solutions for improving the responsivity of photodetectors by integrating plasmonic nanostructures. We applied two methods: (1) generation of hot electrons, and (2) improvement of light absorption. The first method was used to extend the detection bandwidth of the Si photodetectors in the SWIR domain. We used n/n⁺ Si wafers and a simple technology process: bottom Al electrodes deposited and patterned on the backside (Ohmic contacts), and Schottky nanostructured contacts on the front side. The top electrodes consist of interconnected nano-islands that were obtained be depositing thin metal layers (e.g., Ag 15-50 nm thick) and thermal annealing, or by depositing very thin (4-8 nm) discontinuous metal layers. Examples of nanostructured electrodes are given in fig.1a) and b). The incident sub-bandgap photons excite surface plasmons in the nanostructured electrode and generate plasmon-induced hot electrons.

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