Large-area fabrication of nanometer-scale features on GaN using e-beam lithography

This paper presents a time- and cost-effective method for the large-area fabrication of photonic crystals with nanometer-scale features on the GaN material. The proposed technique utilizes e-beam lithography and double hard mask layers to enable the high aspect ratio etching of the nanoscale features. The double hard mask layer, which is a photoresist, platinum (Pt) and SiO2, is very strong against plasma etching, making it an effective barrier layer to protect the underlying material during the etching process. The fabricated photonic crystal exhibits a high aspect ratio and excellent uniformity over a large area. This technique can be used for the time-effective production of photonic crystals for various applications such as optical sensing, spectroscopy, and telecommunications. The method presented in this paper can also be extended to other material systems beyond GaN. The proposed approach provides a promising route to achieve the large-area fabrication of nanometer-scale structures with high aspect ratios using e-beam lithography.