Stabilization of tetragonal/cubic phase in Fe doped zirconia grown by atomic layer deposition

摘要

In this work we investigated the effect of Fe doping on structural properties of ZrO2 grown by atomic layer deposition (ALD) using Zr(TMHD)_4 for Zr and Fe(TMHD)_3 for Fe precursors (TMHD=2,2,6,6-tetramethyl-3, 5-heptanedionate) and ozone as oxygen source. The temperature during the growth process was fixed at 350 °C The ALD process was tuned to obtain Fe-doped ZrO_2 films with uniform chemical composition, as seen by the time of flight secondary ion mass spectrometry. The control of Fe content was effectively reached, by controlling the ALD precursor pulse ratio, as checked by X-ray photoemission spectroscopy (XPS) and spectro-scopic ellipsometry. From XPS, Fe was found in Fe~(3+) chemical state, which maximizes the magnetization per atom. We also found, by grazing incidence X-ray diffraction, that the inclusion of Fe impurities in ZrO_2 induces amorphization in thin ZrO_2 films, while it stabilizes the high temperature crystalline tetragonal/cubic phase after rapid thermal annealing at 600 ℃.