Comparison of the growth behavior of γ-Al2O3 thin films grown on Si (1 1 1) by molecular beam epitaxy using N2O and O2

Epitaxial growth of γ-Al2O3 films was carried out by molecular beam epitaxy (MBE) in either O2 or N2O ambient and with substrate temperature and pressure ranging from 600 to 800 °C and 5×10−4 to 3×10−2 Pa, respectively. Using N2O gas, pits caused by the etching of Si were observed at a gas pressure of 3×10−2 Pa and substrate temperature of 800 °C, and Al droplets were formed at 5×10−4 Pa and 800 °C, while neither pits nor droplets were obtained with O2 under the same growth conditions. This suggests that O2 is a more suitable oxidation gas than N2O for growing epitaxial γ-Al2O3 films.