Bandgap states in transition-metal (Sc, Y, Zr, and Nb)-doped Al2O3

We have investigated the electronic structure of transition-metal (TM=Sc, Y, Zr, and Nb)-doped Al2O3 by x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy (XAS). In valence bands of these TM-doped Al2O3 measured by XPS, the highest occupied levels and the shapes of valence band...

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Bibliographic Details
Published in:Applied physics letters 2003-12, Vol.83 (25), p.5226-5228
Main Authors: Jung, Ranju, Lee, Jae-Cheol, So, Ye-Won, Noh, Tae-Won, Oh, S.-J., Lee, Jong-Cheol, Shin, Hyun-Joon
Format: Article
Language:English
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Summary:We have investigated the electronic structure of transition-metal (TM=Sc, Y, Zr, and Nb)-doped Al2O3 by x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy (XAS). In valence bands of these TM-doped Al2O3 measured by XPS, the highest occupied levels and the shapes of valence bands are almost unchanged from the pure alumina. On the other hand, XAS spectra obtained at the oxygen K-edge show that Nb- and Zr-doped Al2O3 show localized d states in the bandgap below the conduction band minimum, while Y- and Sc-doped Al2O3 have d states inside the conduction band of the original Al2O3. This implies that Y- and Sc-doped Al2O3 will show little bandgap degradation and maintain the same band offset as silica at the Si interface, and can serve as promising candidates for an alternative gate oxide.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.1635656