Simple ALD process for ε-Fe₂O₃ thin films

Atomic layer deposition (ALD) is an advanced industrially feasible technique for fabricating functional materials as high-quality thin films. Here we exploit the technique for the first time for growing thin films of the rare ε-Fe₂O₃ phase that has been found only in nanoscale samples. This single-metal single-valence oxide is receiving increasing interest due to its unusually high coercivity and multiferroic properties. With ALD, polycrystalline thin films of the ε-Fe₂O₃ phase are achieved on various substrate surfaces at a relatively low deposition temperature (260-300 °C) from FeCl₃ and H₂O precursors. The films are ferrimagnetic having an ∼1.6 kOe coercive field.