Improvement of Al2O3/Ge interfacial properties by O2-annealing

The electrical properties of an Al2O3/Ge gate stack structure were improved by O2-annealing. The interface state density can be decreased by O2-annealing without the formation of a GeO2 interfacial layer. X-ray photoelectron spectroscopy measurements revealed that Ge diffusion into the Al2O3 layer occurs and Ge is uniformly distributed in the oxide layer after O2-annealing. Crystallization of the Al2O3 film was observed after O2-annealing at 550 °C and was identified as an Al–Ge–O compound using cross sectional transmission electron microscopy and transmission electron diffraction measurement.