A novel growth technique for GaN films on Si substrates, using metalorganic chemical vapour deposition, was considered. Firstly, Ga droplets were deposited onto a Si substrate by feeding trimethylgallium. The substrate was then heated at 1080C, resulting in the formation of recesses on its surface by melt-back etching. Finally, a GaN film was grown onto the Ga-induced meltback-etched surface using a high-temperature-grown AlN intermediate layer. After the growth of the GaN film, 0.5 to 1μm-diameter pits were observed on the GaN surface. A cathodoluminescence image revealed that low threading-dislocation density regions were successfully grown around the pits.

Reduction of Threading Dislocations in GaN on in situ Meltback-Etched Si Substrates. H.Ishikawa, K.Shimanaka: Journal of Crystal Growth, 2011, 315[1], 196-9