Structure and Non-Equilibrium Phase Diagram of the Co-Sputtered and Post-Annealed Fe-ZnO System

Abstract

X-ray diffraction and electron microscopic studies on co-sputtered Zn_1−xFe_xO single crystalline films showed the solubility limit to be about x=0.50 at 673 K. An increase of Fe greater than 0.50 resulted in the existence of Fe metal and (ZnFe)Fe₂O₄ spinel solid solution in a matrix of (ZnFe)O wurtzite solid solution below a substrate temperature of 573 K. Above a substrate temperature of 673 K, a ZnFe₂O₄ spinel phase rather than a Fe metal phase was seen. Annealing of as-sputtered films with a single phase of Zn_1−xFe_xO in air led to decomposition to the two-phase structure of Zn_1−xFe_xO wurtzite and ZnFe₂O₄ spinel and the decrease of the solubility limit of Fe in ZnO to about x=0.11 at 873 K.