GaN epilayer grown on Ga₂O₃ sacrificial layer for chemical lift-off application

GaN-on-sapphire structure with a Ga₂O₃ sacrificial layer was employed for the chemical lift-off process application. The (201) β-oriented Ga₂O₃ thin film was first deposited on the c-plane sapphire substrate using pulsed laser deposition, followed by the GaN growth via metalorganic vapor phase epitaxy under N₂ and H ₂ environment in sequence. From the transmission-electron-microscopy observation, the orientation relationship between GaN and β-Ga ₂O₃ was identified as GaN [11 20] Ga₂O ₃[010]. A GaN epilayer with an electroplated copper substrate was demonstrated using a chemical lift-off process where the Ga₂O ₃ sacrificial layer can be laterally etched out with a hydrofluoric solution.