Reduction of threading dislocations in GaN on in-situ meltback-etched Si substrates

We report a novel growth technique of GaN films on Si substrates using a metalorganic chemical vapor deposition. First, Ga droplets are deposited on a Si substrate by feeding trimethylgallium. And then the substrate is heated at 1080 °C, resulting in the formation of recesses on its surface by meltback etching. Finally, a GaN film is grown on the Ga-induced meltback-etched surface using a high-temperature-grown AlN intermediate layer. After the growth of the GaN film, 0.5–1-μm-diameter pits were observed on the GaN surface. A cathodoluminescence image reveals that low-threading-dislocation-density regions were successfully grown around the pits.