Multispectral graphene infrared photodetectors using plasmonic metasurfaces

Advanced functional infrared (IR) photodetectors with wavelength selectivity are promising for a wide range of applications, such as multicolor imaging, gas analysis and biomedical analysis. Graphene is considered to be a promising material for novel IR detectors. However, the absorption of graphene is constant at approximately 2.3% and rather small. We have developed multispectral high-performance graphene IR photodetectors using metal-insulator-metal (MIM) or single-layer (SL) plasmonic metasurfaces (PMs). MIM- or SL-PMs induce localized surface plasmons on their surfaces and enhance absorption at the wavelength, which can be controlled by their surface patterns, such as the period or the gaps between micropatches. The absorption of graphene with PMs was theoretically investigated for various structural parameters. The absorption wavelength can be controlled based on plasmonic resonance by varying the surface geometry of the PMs. Graphene-based IR photodetectors with SL-PMs were fabricated by the chemical vapor deposition of graphene and then transferred onto the PMs. Wavelength-selective enhancement of the optical absorption and detection by graphene could be achieved due to the effect of the PMs. The results obtained here are expected to contribute to the realization of multispectral graphene infrared image sensors.