A buffer layer for ZnO film growth on sapphire

An ultra-thin layer of Fe3O4, with a roughly ordered (1 1 1) face, prepared on a Mo(1 1 0) substrate has been used to grow ZnO films under ultra high vacuum condition. In situ X-ray photoelectron spectroscopy and low energy electron diffraction indicate that the ZnO(0 0 0 1) films, with marginal ordering, are epitaxially grown on the Fe3O4(1 1 1) surface. Compared with MgO(1 1 1) layer used to grow ZnO on sapphire, the Fe3O4(1 1 1) might be a better buffer layer owing to the fact that Fe3O4(1 1 1) surface is more thermodynamically stable. In consideration of lattice match and symmetry as well as thermal stability, we predict that both Fe2O3(0 0 0 1) and FeO(1 1 1) layers are also good candidates as buffer layers for ZnO(0 0 0 1) growth on sapphire (0 0 0 1) surface.