Homoepitaxial GaN layers studied by low-energy electron microscopy, atomic force microscopy and transmission electron microscopy

The homoepitaxial growth of GaN(0001) layers was studied in situ and in real time using the low-energy electron microscope, and ex situ using atomic force microscopy and transmission electron microscopy. The growth was conduced on substrates of GAN(0001) deposited on 6H-SiC(0001) by organometallic vapor phase epitaxy. Two growth techniques were employed: one with N atoms supplied by an r.f. plasma source, and the other with NH₃ molecules seeded in a He supersonic beam. The Ga flux was supplied by an evaporative cell in both cases. Under Ga-rich conditions, non-faceted homoepitaxial layers were achieved on Ga precovered substrate surfaces for both growth methods at 665 °C, but the growth morphologies were different.