Control of <scp>Electrohydrodynamic‐</scp>Induced Defects in Nanoimprinted Nanopillars for Optimized <scp>GaN</scp> Pendeoepitaxy

ABSTRACT UV‐assisted nanoimprint lithography (UV‐NIL) has long been recognized as a potential nanopatterning method for polymer surfaces deposited on materials using flexible or solid stamps, enabling the development of micro or nanophotonic systems. However, due to the presence of a surface electrostatic field, electrohydrodynamic (EHD) instabilities, and redistribution of the used polymer can occur, preventing the correct transfer of targeted designs to the surface of the substrate material. In this context, a detailed theoretical and experimental investigation has been carried out to avoid these instabilities and achieve correct polymer patterning without suffering from EHD‐induced defects. Thanks to this analysis, a technical approach has been implemented to successfully fabricate 200‐nm‐wide GaN pillars by plasma etching from a GaN/AlN/Si/SiO 2 stack for high‐quality GaN pendeoepitaxy. Our developed process has yielded pillar arrays with high resolution and zero defects (no missing pillars) over a 36 × 36 mm 2 area. These findings are a significant step toward perfecting both small‐ and large‐scale UV‐NIL nanofabrication of pillar arrays, which holds great promise for the future market of GaN μLEDs with improved photonic performance.