Effect of Al and Y incorporation on the structure of HfO2

X.F. WANG; M.S. MORENO; Q. LI

JOURNAL OF APPLIED PHYSICS

American Institue of Physics

Año: 2008 vol. 104 p. 935291 - 935294

0021-8979

We have investigated the structural changes in HfO2 thin films upon Y and Al incorporation. Thecrystallinity of the films is examined by transmission electron diffraction. The local coordinationsymmetries of the Hf atoms in the films are revealed by the profile of the oxygen K-edge measured in the electron energy loss spectroscopy (EELS). The EEL spectra are then simulated using real-space multiple-scattering method. We found a good agreement between the simulated and the experimental EELS result of the pure HfO2. The Y incorporation indeed stabilized HfO2 to a cubic structure. Nevertheless, it also contributed to possible lattice distortion and/or creation of complex defect states other than O vacancies, causing discrepancies between the experimental and the simulated results. As a comparison, the local symmetry of Hf is largely degraded upon theincorporation of Al, which not only amorphorized HfO2, but also introduced significantly amount of O vacancies in the film.