Millimeter-scale gate-tunable graphene nanoribbon devices as a platform for mid-infrared and bio sensing applications

The experimental observation of graphene plasmon resonance has generated tremendous interest due to numerous potential applications such as photosensors, detectors, biosensors, and switches from THz to mid-infrared regime. However, practical applications require much larger dimensions (mm to cm scale) than that demonstrated in the proof-of-concept devices. Moreover, such devices also require a detailed understanding of ribbon-to-ribbon interaction, which has not been investigated so far. Here we demonstrate gate tunable plasmon resonance in the mid-infrared spectral region on millimeter-scale graphene nanoribbon (GNR) array devices fabricated using graphene monolayer. Gate dependent Fourier-transform infrared (FTIR) transmission measurements on GNR of various widths were investigated experimentally. The shift in plasmon resonance peaks of wave number 100 cm^-1 at applied external gate voltage -100 V was observed. This shift is attributed to strong gate modulation. Our investigation of ribbon-to-ribbon interaction by tuning the aspect ratio reveals strong modulation of surface plasmon resonance peaks in GNR. This suggests that plasmon resonances are coupled as evidenced by blue-shifted plasmon resonance. These studies demonstrate that large-area GNR devices can serve as an ideal platform for ultrasensitive sensing and detector applications.