Study of GaN-Based Thermal Decomposition in Hydrogen Atmospheres for Substrate-Reclamation Processing

This study investigates the thermal decomposition behavior of GaN-based epilayers on patterned sapphire substrates (GaN-epi/PSSs) in a quartz furnace tube under a hydrogen atmosphere. The GaN-epi/PSS was decomposed under different hydrogen flow rates at 1200 °C, confirming that the hydrogen flow rate influences the decomposition reaction of the GaN-based epilayer. The GaN was completely removed and the thermal decomposition process yielded gallium oxyhydroxide (GaO₂H) nanostructures. When observed by transmission electron microscopy (TEM), the GaO₂H nanostructures appeared as aggregates of many nanograins sized 2⁻5 nm. The orientation relationship, microstructure, and formation mechanism of the GaO₂H nanostructures were also investigated.