Mitigation of defects in 10 nm-wide metallic nano-gaps with thermal annealing

초록

Metallic nano-gap structures in the terahertz (THz) frequency range are of increasing interest due to their ability to enhance localized electromagnetic fields, enabling applications in nonlinear optics and sensing. However, lithography-based fabrication processes often leave metallic residues and structural defects around the nano-gap region, which is especially detrimental for very narrow (similar to 10 nm) gaps. In this study, we apply a thermal annealing process to mitigate these issues and analyze its effects at various temperatures. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) show that annealing reduces surface roughness and removes residual metals, improving structural consistency. The annealing also increases transmittance and blue-shifts the resonance frequency of the THz nano-gaps, which indicates removal of the occasional metallic bridges blocking the gap. These results demonstrate that thermal annealing is a simple and effective post-treatment method for improving the performance of nano-gap-based THz devices.

키워드