Microstructural analysis of aluminum nitride modified by femtosecond laser surface processing

Self-organized laser functionalization (SOLF) using femtosecond pulses presents a powerful, singlestep strategy for tuning the surface chemistry and structure of ceramic materials. In this study, aluminum nitride (AlN) substrates were irradiated with ultrashort laser pulses, producing selforganized quasi-periodic mound-like surface micro- and nano-scale structures driven by preferential ablation, nanoparticle generation, transport, and redeposition. The resulting nanoparticles (~100 nm) that overlay the microscale features were identified as oxygen-rich alumina phases formed through laser-induced oxidation under ambient conditions. A thin Al₂O₃-enriched interfacial layer was hence observed, arising from phase transformation within the SOLF-processed AlN substrate. These results establish SOLF as a scalable pathway for engineering functional AlN surfaces and highlight its potential in next-generation thermal management, power electronics, and packaging technologies.