Optimizing GaN Surface Morphology through Controlled Photo-Electroless Etching for Enhanced Optical Properties

Nanostructured gallium nitride (GaN) shows strong potential in enhancing ultraviolet (UV) photodetectors through improved sensitivity and in light-emitting diodes (LEDs) via better spatial resolution. It is also promising for quantum photonics, particularly as a scalable, room-temperature single-photon emitter vital for quantum communication and sensing. A cost-effective photo-electroless etching (PEE) technique was employed to fabricate various GaN nanostructures, including vertically aligned nanowires (NWs) with a mean length of 1.75 ± 0.21 μm and a diameter of 39.36 ± 11.28 nm, as well as complex nano- and microporous layers. The study evaluated how different illumination conditions, power levels, and etching durations influenced the etching efficiency and surface morphology. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses revealed the transition from porous layers to vertical NWs, which eventually detached from the substrate. Energy-dispersive X-ray spectroscopy (EDX) confirmed that the structures consist primarily of gallium and nitrogen, consistent with GaN composition, while photoluminescence (PL) and cathodoluminescence (CL) spectroscopies were employed to investigate their optical properties. The efficiency of UV photon emission relative to visible emission was quantified, revealing a strong dependence on the morphology. These results prove how PEE enhances photon extraction, positioning GaN as a versatile platform for future quantum technologies.