Synergistic Enhancement Mechanism of High Electron Density and Localized Surface Plasmons for Strong Light-Matter Interactions

2D layered semiconductor materials hold the potential to address the crucial technical challenges of poor signal uniformity and low repeatability of traditional metal plasmonic nanostructures in sensing, which hinder quantitative detection and analysis in molecular detection. However, the ultra-low light absorption efficiency and electronic state density intrinsically result in their inferior sensitivity compared with those of conventional metal plasmonic nanostructures. Therefore, the integration of the classical back-gate modulation strategy and surface plasmon resonance into 2D heterostructures is proposed. This integration aims to control the interaction between the surface sensing material of the heterostructure and target molecules from the perspective of surface electronic state density and optical absorption efficiency. The sensitivity (& AP;10-12 m) of as-designed MoS2/graphene/Ag heterojunction is comparable to that of advanced metal plasmonic nanostructures, and the corresponding enhancement factor (EF, 1.71 x 104) is much higher than that of most heterojunction-based and metal-semiconductor coupled devices. This study uncovers the internal mechanism of the surface plasmon effect and high electronic state density in enhancing light-matter interactions, and provides an alternative avenue for high-performance surface-enhanced devices. The ultra-low light absorption efficiency and electronic state density of 2D layered semiconductor materials seriously limit their sensing sensitivity to biochemical molecules. The integration of back-gate modulation strategy, surface plasmon, and 2D heterostructures provides an alternative avenue for controlling the interaction between surface sensing material and target molecules from the perspective of surface electronic state density and optical absorption efficiency.image