MOCVD Growth of GaN on Sapphire Using a Ga2O3 Interlayer

Metalorganic chemical vapor deposition (MOCVD) was used to grow crystalline GaN on a Ga 2 O 3 interlayer deposited by pulsed laser deposition. The Ga 2 O 3 interlayer situated between undoped GaN (u-GaN) and sapphire can be etched out during the chemical lift-off process. A ( ) oriented β-Ga 2 O 3 thin film was first deposited on the sapphire; this was followed by u-GaN growth via MOCVD carried out in an N 2 atmosphere to prevent the decomposition of Ga 2 O 3 . Using transmission electron microscopy (TEM), the orientation relationship was observed to be GaN[ ]∥Ga 2 O 3 [ ] 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 GaN/Ga 2 O 3 /sapphire were 1444 arcsec and 8.3 nm, respectively; these were almost identical to the measured values for GaN/sapphire fabricated in an N 2 environment. It was concluded that the growth atmosphere played a more important role in determining the crystallinity of u-GaN than the Ga 2 O 3 thin film underneath. Finally, an InGaN light-emitting diode structure was successfully fabricated on the GaN/Ga 2 O 3 /sapphire.