Morphology and interface structure of α-Fe2O3 islands grown on sapphire by ion-implantation and annealing

The morphology and interface structure of α-Fe2O3 islands grown on α-Al2O3 single crystals (sapphire) by Fe-ion-implantation and annealing in an oxidizing atmosphere have been studied using transmission electron microscopy. The α-Fe2O3 islands have the orientation relationship of [0001]α-Fe2O3||[0001]sapphire and (112¯0)α-Fe2O3||(112¯0)sapphire with sapphire. The typical outline of α-Fe2O3 islands consists of two (0 0 0 1) and six {101¯2} planes. The interfaces between α-Fe2O3 islands and sapphire are semicoherent, that is coherent regions separated by misfit dislocations at the interfaces. When imaged along the [1¯100]sapphire direction, the projected Burgers vector is determined to be 16[112¯0]sapphire. When imaged along the [112¯0]sapphire direction, the projected Burgers vector is determined to be 12[1¯100]sapphire. These misfit dislocations form a network structure at the interface to accommodate the mismatch between the lattices of the α-Fe2O3 and the α-Al2O3.