Comparison of GaP and Si nanoantennas for optical emission control

Nanostructures made of high-refractive-index materials present a novel technological platform for efficient light manipulation at the nanoscale. Among all materials compatible with the currently available fabrication techniques, Si and GaP are the most suitable for the visible spectral range. Here, we consider a system consisting of a luminescent diamond nanoparticle with embedded color centers emitting light, placed on top of a Si or GaP cylindrical nanoantenna. We study theoretically how dielectric nanoantennas affect the emission properties of the system and predict a several-fold enhancement of the spontaneous emission rate of a single emitter located inside an optically small diamond nanoparticle. We compare performance of the two considered materials in different parts of the visible spectrum and find that for single dipole sources that emit at the blue end of the spectrum, it is beneficial to use GaP nanoantennas, while silicon becomes the material of choice for emitters at the red end of the spectrum.