Highly sensitive all-silicon plasmonic metasurface for CO₂ detection applications

Accurately detecting carbon dioxide (CO2) gas holds significant importance in various domains, including clinical, environmental, biological, biochemical, and industrial sectors. These areas encompass applications in clinical settings, environmental studies, biological research, and biochemical and industrial fields. Surface plasmon polariton (SPP) resonant sensors have found wide-ranging applications, particularly for nanoscale biosensing. The dispersion of SPP is influenced by a particular set of metal characteristics that cannot be randomly adjusted. The proposed sensor is based on SPP metamaterial, and it operates as a plasmonic sensor specifically designed with a metal-air interface. This study introduces a highly sensitive silicon (Si) grating consisting of metal, dielectric, and metal (MDM) layers. The metallic layer is made of doped silicon (D-Si) material, while the dielectric layer consists of Si and Si3N4. Silicon offers several benefits, such as its compatibility with the technology of complementary metal-oxide-semiconductor (CMOS) and easy manufacture using traditional silicon fabrication techniques. Our proposed structure exhibits high sensitivity at a wavelength range of 12 µm to 14 µm in the infrared range (IR). We have introduced a metasurface plasmonic sensor as a sensing system to detect micro changes in the refractive index. To assess its performance, simulations using commercial finite difference time domain techniques were performed. By analyzing the resonant reflection spectra in various regions of the non-Hermitian eigenmode space, we evaluated the sensing capabilities of the plasmonic grating. This device holds potential for gas detection applications.