Comprehensive Study of Scattering and Electric Field Modulation in WS2 Nanoantennas with Varying hBN Thickness

Abstract

Hybrid nanoantennas represent one of the promising applications within the field of nanophotonics. They combine multiple materials in an attempt to increase the efficiency of light-matter interaction. Among the proposed materials that could be implemented in such systems, TMDs, such as WS₂, are widely used. WS₂ belongs to the family of Van der Waals materials featuring a crystal structure with layers held together by weak Van der Waals forces. These materials exhibit a high refractive index, which allows better light confinement and enhancement of the light-matter interaction in nanoscale systems. In addition, the layer of hBN exhibits crystal defects that fulfill the emission of single photons, ideal for quantum photonics applications. Such hybrid combinations offer enormous advances in controlling light confinement and electric fields; therefore, it is a basic technology platform for further nanoscale advances. The current study will explore hybrid systems of WS₂ nanoantennas with an added hBN layer on a gold substrate. Geometric dimensions are considered regarding the scattering behavior and electric field distribution. The simulation was performed to investigate the effects of the height and radius of nanoantennas on the comparative performance of the system with and without the presence of an hBN layer. It is seen from the results that, upon increasing the height of a nanoantenna, a better confinement of light thereby achieves sharper and more distinctive resonant peaks at longer wavelengths. Just like that, an increase in the radius then causes the redshift in the resonant peaks, which increases interaction between the light and material with increasing intensity of scattering. The addition of the hBN layer significantly increased the effects of the scattering values. In the Layer configuration, hBN diminished the intensity of the scattering, shifting resonant peaks towards longer wavelengths. Whereas in the configuration with the Polygon shape, it became more stable and enhanced the scattering at a shorter wavelength, attributing to higher efficiency in the confinement of light and material interaction. It was also shown in the present study that the hBN layer affects electric field confinement: the greater its thickness, the lower the maximum intensity of the electric field, and peak values are shifted towards shorter wavelengths. Also, for increasing the electric field, the polygon-shaped configurations of the hBN layer were found to be better in performance than the configuration of a continuous layer. The optimal dimensions for a nanoantenna giving the highest electric field value at 750 nm of wavelength were a thickness of the hBN layer of 5 nm, WS₂ height of 80 nm, and radius of 210 nm, with an electric field value of 2000. This work points out the huge perspectives for hybrid systems in the nanophotonic technological development related to accurate geometric dimensions and materials, such as hBN.