High quality Al 0.99 Ga 0.01 N layers on sapphire substrates grown at 1150 °C by metalorganic vapor phase epitaxy

Abstract We systematically investigated metalorganic vapor phase epitaxy (MOVPE) growths of AlN layers with trimethylgallium (TMGa) supply on sapphire substrates at 1100–1250 °C. We found that Ga incorporations into the AlN layers contributed to smooth surfaces covered with step terraces at the early stage of the Al(Ga)N growth. In addition, a GaN mole fraction leading to the smooth surfaces was found to be around 2–3% at the beginning of growth. The Ga supply during the AlN layer growth at 1150 °C provided very smooth Al 0.99 Ga 0.01 N layers on sapphire substrates.