The mechanism study of highly sensitive gas sensing based on double-layer graphene plasmons

Abstract

The gas sensing based on graphene plasmons enhanced infrared absorption has the advantages of label-free identification of gas molecules, low loss and tunability. However, the optical field confinement of graphene plasmons is much smaller than distribution range of gas molecules, resulting in weak interaction between graphene plasmons and gas molecules. It is difficult to significantly improve the sensitivity of gas sensing. A gas sensor based on double-layer graphene nanoribbons with enhanced plasmons is proposed to improve the near-field coupling between highly confined field and gas molecules. Meanwhile, the influence mechanism of trapping free-gas molecules via surface adsorption is explored on increasing the sensitivity of gas sensing. The results show that the vibrational absorption enhancement of gas molecules based on double-layer graphene nanoribbons is improved by at least an order of magnitude than the single-layer graphene. The surface adsorption by graphene which tunes the gas concentration close to graphene can change the mode weight of vibrational mode to improve the sensitivity further. This study provides an important theoretical basis for designing and preparing gas sensor based on two-dimensional materials plasmons enhanced infrared absorption, and promotes the development of highly sensitive and integrated gas