Atomic Layer Deposition of BiFeO3 Thin Films Using β-Diketonates and H2O

Bismuth ferrite (BiFeO3) thin films were grown by atomic layer deposition (ALD) by combining ALD of Bi2O3 and Fe2O3 and monitored by in-situ quartz crystal microbalance (QCM). The physical and chemical mechanisms of ALD of BiFeO3 were studied according to the results of in-situ QCM and indicate that the deposition of Bi-O and Fe-O were self-limited by molecular sizes of precursors and chemical absorption between precursors and hydroxyl groups. Pure Bi3+ and Fe3+ with atomic ratio of 1:1 were formed during the ALD, and no evaporation of Bi atoms was found at 250 degrees C by X-ray photoelectron spectroscopy (XPS). Pure rhombohedral phase was formed in BiFeO3 films after annealing at 650 degrees C by using X-ray diffraction (XRD). Polarization property of the ALD BFO film was observed and studied by using piezoresponse force microscopy (PFM). The ALD growth of BFO films demonstrates that ALD is an advanced deposition technique for BFO film preparation and memory device application.