Growth of epitaxial γ-Al2O3(111) films using an oxidized Si(111) substrate

High-quality epitaxial γ-Al2O3(111) films were grown on a Si(111) substrate covered with a chemically formed 2 nm SiO2 layer using reactive ionized beam deposition. An epitaxial γ-Al2O3 layer was formed at above 800 °C, while the films showed polycrystalline below this temperature. Al2O3 films grown on an oxidized Si substrate showed a better crystalline quality, a more flat surface and a sharper interface than the films grown on a clean Si substrate. A thin SiO2 layer acts as a barrier to prevent a direct reaction of incident Al with Si substrate, the thin layer is consumed during the Al2O3 growth to yield an abrupt Al2O3/Si interface. The role of the thin oxide layer on the film growth and the chemical reactions at the interface during the initial growth of Al2O3 were investigated.