Dislocation network driven structural relaxation in hematite thin films
Résumé
Using surface X-ray diffraction, we investigated 20 nm thick alpha-Fe2O3(0 0 0 1) thin films deposited on alpha-Al2O3(0001) and Pt(111) single crystals. The films were grown in identical conditions by atomic oxygen assisted molecular beam epitaxy techniques. Both substrates offer close lattice parameter misfits. On sapphire an isostructural epitaxial relationship is observed and a 30 degrees in plane rotation of the lattice for Pt(111). The crystalline quality of the film deposited on Pt(111) is much better and contained less parasitic contributions. The improved crystalline quality of alpha-Fe2O3(0001) layers on Pt(111) is attributed to the presence of a very well ordered interfacial dislocation network which is missing when alpha-Al2O3 is used as substrate. (C) 2007 Elsevier B.V. All rights reserved.