Polarity and surface structural evolution of iron oxide films

Various ordered Fe oxide films were prepared in an ultrahigh vacuum system, and their surface and electronic structure were studied in situ by low-energy electron diffraction and photoelectron spectroscopy. We obtain Fe2O3(0001) films with oxygen termination (O-Fe2O3(0001)), a polar surface, via FeO(111) films. The O-Fe2O3(0001) films can be transformed to a non-polar surface of iron-terminated Fe2O3(0001) (Fe-Fe2O3(0001)) films.Fe3O4(111) films are formed after annealing O-Fe2O3(0001) films. A co-existed phase of Fe-Fe2O3(0001) and Fe3O4(111) is observed via annealing Fe-Fe2O3(0001) films. These Fe oxide films with different surface structures and properties can be designedly used as model plates for further studies in surface physics and chemistry.