Ultrasensitive Deep-Ultraviolet Surface Plasmon Resonance Sensors Using Aluminum-Graphene Metasurface: a Theoretical Insight

This study investigates a versatile deep-ultraviolet (DUV) surface plasmon resonance (SPR) sensor by integrating a few graphene layers into low-cost aluminum (Al) thin film. The high-quality SPR sensing performance can be obtained by tuning the thickness of the aluminum film and graphene layers which creates a phase modulation. Using deionized water (nwater = 1.333) as sample solvent, the best SPR configuration is achieved using a 13-nm Al film decorated with 4-layer graphene. This generated the sharpest differential phase (72.2839o) and darkest minimum reflectivity (1.6985 × 10−7). Meanwhile, the highest detection sensitivity is almost 6.0237 × 104 degree/RIU (RIU, refractive index unit), which is enhanced by almost 5.44 times compared with the bare 19-nm Al film–based sensors. More importantly, our proposed architectures have excellent capability of versatile sensing, which can provide an ultra-high detection sensitivity not only in air medium (nair = 1.000, 6.6667 × 104 degree/RIU) but also in an organic liquid (1,1,1,3,3-hexafluoro-2-propanol solution (HFIP), nHFIP = 1.275, 7.7380 × 104 degree/RIU). We believe that the proposed DUV-SPR sensors could work in various situations, making it a highly promising candidate for designing novel gas and biochemical sensors in deep-ultraviolet region.