Iron oxide on (001) MgO

Transmission and scanning electron microscopy have been used to characteriz e thin films of Fe oxide grown on (001)-oriented MgO using pulsed-laser dep osition. Several films, each with a longer deposition time, and hence incre asing thickness, were grown under similar conditions of oxygen pressure, de position rate and substrate temperature. For shorter deposition times, i.e. thinner films, a spinel-structured Fe oxide film occurred, while for longe r deposition times a corundum-structured Fe oxide film formed. In some inst ances it was found that the film had a mixture of the two structures of Fe oxide. The analysis of these films determined that the corundum-structured Fe oxide was being formed via a transformation from the spinel structure. T his transformation process led to interesting thin-film morphologies and ep itactic alignments.