Misfit dislocations at the single-crystal Fe₂O₃∕Al₂O₃ interface

The buried interface of epitaxially grown α-Fe₂O₃(0001)∕α-Al₂O₃(0001) has been studied using ion-scattering techniques and high-resolution transmission electron microscopy (HRTEM). The results reveal the existence of disordering at the interface attributed to misfit dislocations associated with lattice mismatch between the substrate and the film. Molecular dynamics (MD) calculations were carried out to understand the formation of misfit dislocations and the interface structural features. The calculations show that misfit dislocations form in the Al₂O₃ substrate and terminate at the interface, consistent with the experimental observations. Snapshots of the atomic positions generated by the MD calculations were used in Monte Carlo simulations of the ion channeling experiments. The hitting probabilities determined from these simulations are compared with the experimental surface and interface peaks obtained from the aligned Rutherford backscattering spectrometry (RBS) spectra. Combination of MD and the ion scattering simulations with RBS and HRTEM measurements show promising results in understanding the interface structures of this single crystal Fe₂O₃∕Al₂O₃.