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Title: Effect of Al addition on the microstructure and electronic structure of HfO₂film
Authors: Wang, X. F.
Li, Quan
Egerton, R. F.
Lee, Pui-fai
Dai, Jiyan
Hou, Z. F.
Gong, X. G.
Subjects: Aluminium
Hafnium compounds
High-k dielectric thin films
Crystal microstructure
Short-range order
Amorphous state
Electron energy loss spectra
Band structure
Issue Date: 1-Jan-2007
Publisher: American Institute of Physics
Source: Journal of applied physics, 1 Jan. 2007, v. 101, no. 1, 013514, p. 1-5.
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 HfO₂to pure Al₂O₃by 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 Al/Hf 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 HfO₂and Al₂O₃. 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 (Al/Hf~5.8), in which case the bonding is similar to that in pure Al₂O₃. Although the local symmetry of Hf in amorphous HfO₂is 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 HfO₂.
Rights: © 2007 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in X. F. Wang et al., J. Appl. Phys. 101, 013514 (2007) and may be found at
Type: Journal/Magazine Article
DOI: 10.1063/1.2405741
ISSN: 0021-8979 (print)
1089-7550 (online)
Appears in Collections:MRC Journal/Magazine Articles
AP Journal/Magazine Articles

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