A theoretical approach to develop a black phosphorous coated multilayer plasmonic sensor by using hafnium oxide as dielectric spacer

A multilayered dual-mode plasmonic sensor was theoretically modeled under a spectral interrogation scheme. The proposed sensor was uniquely designed by using hafnium oxide (HfO2) as spacer material between two gold (Au) thin films and few layers of black phosphorus (BP) coating on the top surface. It is observed that the BK7/Au/HfO2/Au/BP sensor exhibits two plasmon modes, among which one responds to refractive index variation of the analyte while the other mode shows no significant shifting indicating the self-referencing ability. An intense electric field with long evanescent waves up to 300 nm was observed at BP/analyte interface. The sensor's performance was tested further using refractive index sensing and the observed sensitivity was 1692 nm/RIU with excellent linear response. A single-layer sensing system was also included in the study to compare the sensitivity with the proposed sensor. The present research will be advantageous in fabricating a multilayer plasmonic sensor with self-referencing potential and allows highly sensitive detection compared to conventional SPR sensors. (C) 2021 Elsevier Ltd. All rights reserved.