Nanoantennas and metasurfaces tailored by electron beam lithography and substrate conductivity.

The precision and reproducibility in the fabrication of periodic nanoantenna arrays are crucial for metasurfaces to achieve consistent and controllable optical responses, and electron beam lithography (EBL) enables this by providing patterning with high resolution down to the nanoscale. This work explores the impact of EBL exposure on the size and uniformity of nanoantennas in periodic arrays, with a focus on the role of substrate conductivity. By systematically comparing substrates with different levels of electrical conductivity, we examine how variations in electron scattering and charge accumulation affect the precision and dimensional control of the fabricated nanoantennas. We show that exposure can efficiently tune the optical characteristics of metasurfaces composed of such nanoantennas, with various multipolar resonances appearing in the spectra of the titanium-based metasurfaces. Titanium is chosen as a nanoantenna material because it provides robust operation in high-temperature environments and biologically relevant applications, while the supported multipolar resonances enhanced by the collective effect offer a versatile platform for engineering the metasurface spectral response. We demonstrate how substrate conductivity influences patterning outcomes, metasurface multipolar resonances, and manifestation of generalized Kerker effect, highlighting the need to carefully select exposure parameters and the underlying material. This work provides insights to improve the fabrication of periodic nanoantenna arrays, ensuring uniformity and consistent optical performance of the metasurfaces based on them.