Fabrication of three-dimensional microstructures on GaN surfaces through the integration of femtosecond laser ablation and ICP etching

Gallium nitride (GaN) surface microstructures are crucial for enhancing the performance and reliability of highpower devices. However, the direct fabrication of patterned three-dimensional (3D) microstructures on GaN surfaces remains a significant challenge. This paper introduces an innovative approach, employing a maskless femtosecond laser combined with inductively coupled plasma (ICP) etching, to efficiently fabricate petal-shaped 3D microstructures on GaN surfaces. By fine-tuning the ICP etching and femtosecond laser parameters, we have obtained the regularities of the dimensional variations of these 3D microstructures. Additionally, our investigation reveals that the design of microstructural concavity and convexity characteristics can be flexibly manipulated by controlling the ICP etching rate, which is influenced by the oxide content in the laser-modified zone. This study presents a novel method for straightforward fabrication of microstructures on gallium nitride surfaces.