Electromechanically reconfigurable plasmonic photodetector with a distinct shift in resonant wavelength.

Plasmonic photodetectors have received increasing attention because their detection properties can be designed by tailoring their metal structures on surfaces without using any additional components. Reconfiguration of the plasmonic resonant state in a photodetector is relevant for various applications, including investigating in situ adaptive detection property changes, depending on the situation, and performing single-pixel spectroscopy in geometrically limited regions. However, the spectral responsivity change with conventional reconfiguration methods is relatively small. Here, we propose a plasmonic photodetector that reconfigures its spectral responsivity with electromechanical deformation instead of bias tuning. The photodetector consists of a gold plasmonic grating formed on an n-type silicon cantilever, and the spectral responsivity is reconfigured by electromechanically scanning at an incident angle to the grating on the cantilever. The photodetector exhibits peak shifts in spectral responsivity in a wavelength range from 1250 to 1310 nm after electromechanical reconfiguration. Finally, for potential future applications, we demonstrate near-infrared spectroscopy using the photodetector. This photodetector has the potential to be adopted as a near-infrared spectrometer in industrial silicon imaging systems because its structure enables subbandgap photodetection on silicon by a Schottky junction.