Graphene vs. silica coated refractory nitrides based core-shell nanoparticles for nanoplasmonic sensing.

Plasmonic nanoparticles based on conventional metals like gold (Au) and silver (Ag) has attracted significant attention of biosensor researchers. Core-shell nanoparticles (CSNP) have shown specific advantages by virtue of unique combination of strong field enhancement and wide ranging spectral tuneability of localized surface plasmon resonances (LSPR). In view of the remarkable plasmonic properties of refractory nitrides (e.g., ZrN and TiN) like higher degree of spectral tuneability, growth compatibility, high melting point, inherent CMOS and biocompatibility etc., and reported high surface area, excellent bio-molecular compatibility, improvement in the speed, higher sensitivity in graphene, the present work assess the feasibility of graphene coated refractory nitrides based CSNP as an efficient refractive index sensor. Mie theory is employed for the theoretical analysis and simulation of such plasmonic structures. The results reported in the present work have been corroborated using COMSOL. The comparison of plasmonic properties and sensing characteristics e.g., FWHM, quality factor, sensitivity and figure of merit is presented for graphene and silica based sensors. It is reported that the sensitivity = 171.68 (nm/RIU) and figure of merit = 3.57 × 104 (nm/RIU) can be attained. The present work suggests that graphene coated refractory nitrides based core-shell structures may emerge as ultrasensitive biosensor.