MOCVD growth of GaN on sapphire using a Ga₂O₃ interlayer

Metalorganic chemical vapor deposition (MOCVD) was used to grow crystalline GaN on a Ga₂O₃ interlayer deposited by pulsed laser deposition. The Ga₂O₃ interlayer situated between undoped GaN (u-GaN) and sapphire can be etched out during the chemical lift-off process. A (201) oriented -Ga₂O₃ thin film was first deposited on the sapphire; this was followed by u-GaN growth via MOCVD carried out in an N₂ atmosphere to prevent the decomposition of Ga₂O ₃. Using transmission electron microscopy (TEM), the orientation relationship was observed to be GaN1120Ga₂O₃010 where the lattice mismatch between the two materials was 8.5. The full width at half maximums of the x-ray rocking curve at the GaN (0002) plane and of the photoluminescence spectrum measured from GaNGa₂O₃sapphire were 1444 arcsec and 8.3 nm, respectively; these were almost identical to the measured values for GaNsapphire fabricated in an N₂ environment. It was concluded that the growth atmosphere played a more important role in determining the crystallinity of u-GaN than the Ga₂O₃ thin film underneath. Finally, an InGaN light-emitting diode structure was successfully fabricated on the GaNGa₂O₃sapphire.