  Optoelectronic functionalities of photodection and light harnessing rely on
the band-to-band excitation of semiconductors, thus the spectral response of
the devices is dictated and limited by their bandgap. A novel approach, free
from this restriction, is to harvest the energetic electrons generated by the
relaxation of a plasmonic resonance in the vicinity of a metal-semiconductor
junction. In this configuration, the optoelectronic and spectral response of
the detectors can be designed ad hoc just by tailoring the topology of metal
structures, which has tremendous applications in solar energy harvesting and
photodetection. Fully exploiting hot electron based optoelectronics yet
requires a platform that combines their exotic spectral capabilities with large
scale manufacturing and high performance. Herein we report the first
implementation of a large area, low cost quasi 3D plasmonic crystal (PC) for
hot electron photodetection, showcasing multiband selectivity in the VIS-NIR
and unprecedented responsivity of 70 mA/W.
