Growth of α-Al2O3 films by molecular layer epitaxy

Single-crystal α-Al2O3 films are, for the first time, successfully grown on sapphire wafers above ∼600 °C by the molecular layer epitaxy (MLE) method using AlCl3 vapor and a He 15%O2 gas mixture. The average growth rate observed barely depends on the substrate temperature, being ∼0.09 nm per cycle of gas transport, under the used growth conditions. The epitaxial growth of α-Al2O3 films on single-crystal Nb films at ∼500 °C by the MLE method is also confirmed for the first time.