Al2O3 films were prepared by atomic layer deposition using trimethylaluminum and H2O at 250 °C on 4H-SiC substrates and annealed at 1000 °C in N2. The as-deposited and annealed Al2O3 films were measured and analyzed near the Al2O3/SiC interfaces by using an X-ray photoelectron spectroscopy (XPS) with etching processing. The XPS results showed that as-deposited Al2O3 films were O-rich and converted to anhydride Al2O3 films after annealed at 1000 °C in N2. Si suboxides were found both at as-deposited and annealed Al2O3/SiC interfaces. Energy band shift between Al2O3 and 4H-SiC was found after annealing. The conduction band offsets of as-grown and annealed Al2O3/SiC were 1.90 and 1.53 eV, respectively. These results demonstrated that Al2O3 can be a good candidate to be applied in SiC metal-oxide-semiconductor devices.

Bismuth ferrite (BiFeO 3 ) thin films were grown by atomic layer deposition (ALD) by combining ALD of Bi 2 O 3 and Fe 2 O 3 and monitored by in-situ quartz crystal microbalance (QCM). The physical and chemical mechanisms of ALD of BiFeO 3 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 Bi 3+ and Fe 3+ with atomic ratio of 1:1 were formed during the ALD, and no evaporation of Bi atoms was found at 250 °C by X-ray photoelectron spectroscopy (XPS). Pure rhombohedral phase was formed in BiFeO 3 films after annealing at 650 °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.

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