Improving the Refractive Index Sensitivity of Triangular Gold Nanoprisms by Reducing the Substrate Effect

The dependence of the surface plasmon resonance frequency on the change in the permittivity of the medium near metal nanostructures opens up the possibility of using them as a universal platform for creating biochemical sensors. Improving the sensitivity of such systems makes it possible to detect the smallest change in the refractive index upon the adsorption of a small amount of analyte on the surface of plasmonic nanoparticles. One of the approaches to improve the sensitivity of nanostructure arrays is to reduce the effect of the substrate. Upon excitation of surface plasmon resonance, a significant part of the locally enhanced electric field, which determines the possibility of detection, is located in the volume of the substrate material and is inaccessible to analyte molecules. We studied the sensitivity of an array of gold triangular nanoprisms to a change in the refractive index of a medium depending on the height of an extra dielectric layer under the particles using finite difference numerical simulation in the time domain. The sensitivity reaches 42 +/- 6% at a layer height of 15 nm, while a further increase in the spacer thickness does not significantly increase the sensitivity of the system.