Effect of Al addition on the microstructure and electronic structure of Hf O2 film

X. F. Wang, Quan Li, R. F. Egerton, P. F. Lee, J. Y. Dai, Z. F. Hou, X. G. Gong

Research output: Journal article publicationJournal articleAcademic researchpeer-review

20 Citations (Scopus)

Abstract

We have investigated the microstructures and electronic structures of a series of hafnium aluminate (HfAlO) films with Al concentration ranging from 0% to 100%. When the films evolve from pure Hf O2 to pure Al2 O3 by increasing the aluminum content, we find changes in their radial distribution functions, which disclose the short-range order of the materials, despite the amorphous nature of all films. The HfAlO films (with AlHf ratio ranging from 0.25 to 5.8) appear to be a single glassy phase of Hf, Al, and O, instead of simple mixtures of Hf O2 and Al2 O3. The Hf (Al)-O, Hf (Al)-Al, and Hf-Hf bonds are observed to be insensitive to the amount of Al in the film, except when the Al concentration is large (AlHf∼5.8), in which case the bonding is similar to that in pure Al2 O3. Although the local symmetry of Hf in amorphous Hf O2 is suggested by the electron energy-loss spectrum taken at an oxygen K edge, it is largely disrupted when Al is introduced. The valence electron energy-loss spectroscopy reveals three distinct evolving features as the Al content increases, which we discuss in terms of the electronic structure of Hf O2.
Original languageEnglish
Article number013514
JournalJournal of Applied Physics
Volume101
Issue number1
DOIs
Publication statusPublished - 24 Jan 2007

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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