Zn1−xFexO films: from transparent Fe-diluted ZnO wurtzite to magnetic Zn-diluted Fe3O4 spinel

Abstract

The different phases formed in Zn_1−xFe_xO thin films where x varies from 0 to 1, as well as their structural characteristics and physical properties, have been investigated. In particular, the interrelationships between the iron concentration, the oxygen composition and the microstructure of the films have been determined. The Zn_1−xFe_xO films were grown on c-cut sapphire substrates by pulsed-laser deposition. For 0 < x < 0.35, epitaxial films with a wurtzite (ZnO like) structure were obtained, while for 0.65 < x < 1, spinel (Fe₃O₄ like) epitaxial films were observed. In the intermediate region (0.35 < x < 0.65) the phase separation of the Zn_1−xFe_xO films leads to the formation of both wurtzite and spinel phases. Whatever is the x value, the films display well-defined in-plane epitaxial relationships between the wurtzite (or spinel) phase and the substrate. The optical, electrical and magnetic properties of the Zn_1−xFe_xO films are discussed in relation with their structural characteristics.