Femtosecond Laser Slicing of Single Crystal AlN Layer Grown by Hydride Vapor Phase Epitaxy on an AlN Substrate Generated by Physical Vapor Transport

Aluminum nitride (AlN) is one of the highly anticipated materials for deep-ultraviolet (UV) optoelectronic devices due to its wide-bandgap and high thermal conductivity. Growing a thick single-crystal AlN layer by Hydride Vapor Phase Epitaxy (HVPE) method on another AlN substrate generated by Physical Vapor Transport (PVT) method is an effective method to obtain pure single crystal AlN. However, the waste of PVT-AlN is a serious obstruct for industrialization. In this study, the laser slicing of HVPE-AlN and PVT-AlN by femtosecond laser pulses was performed. The surface roughness of the separated HVPE-AlN was smaller than 120[micro]m, while the separated PVT-AlN substrate was successfully used to grown a new single crystal AlN by HVPE after polishing. Femtosecond laser double spots scanning by using a SLM was also investigated to improve the efficiency. Keywords: ultrashort pulse laser processing, aluminum nitride, kerf loss, reuse of substrate, double spot laser slicing