2005
DOI: 10.1109/tdmr.2005.845804
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Conduction band-edge States associated with the removal of d-state degeneracies by the Jahn-Teller effect

Abstract: X-ray absorption spectroscopy (XAS) is used to study band edge electronic structure of high-transition metal (TM) and trivalent lanthanide rare earth (RE) oxide gate dielectrics. The lowest conduction band d-states in TiO 2 , ZrO 2 and HfO 2 are correlated with: 1) features in the O K 1 edge, and 2) transitions from occupied Ti 2p, Zr 3p and Hf 4p states to empty Ti 3d-, Zr 4d-, and Hf 5d-states, respectively. The relative energies of d-state features indicate that the respective optical bandgaps, E opt (or eq… Show more

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Cited by 68 publications
(55 citation statements)
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“…Electrical transport properties were measured ex situ with a Quantum Design physical properties measurement system using the van der Pauw geometry, taking appropriate precautions to avoid photoinduced carriers. NEXAS and vis-VUV-SE are described elsewhere [8,9].…”
mentioning
confidence: 99%
“…Electrical transport properties were measured ex situ with a Quantum Design physical properties measurement system using the van der Pauw geometry, taking appropriate precautions to avoid photoinduced carriers. NEXAS and vis-VUV-SE are described elsewhere [8,9].…”
mentioning
confidence: 99%
“…45 Such grain boundary defects have been assigned to Jahn-Teller term d-state splitting of bulk nanocrystallites. These reports appear consistent with the x-ray diffraction data showing the presence of erbium silicate nanocrystallites.…”
mentioning
confidence: 99%
“…[4]. These include remote plasma-assisted chemical vapor deposition (RPECVD) for the TM elemental oxides, and reactive evaporation for the TM elemental and TM/RE complex oxides.…”
Section: Experimental Methodsmentioning
confidence: 99%
“…These assignments differentiate between intrinsic band edge states of the bulk oxide film with anti-bonding and localized d-character, and localized states of a different origin, in this instance, defect states postulated to be at grain boundaries of the nanocrystalline films. These assignments are based on comparisons between X-ray absorption spectroscopy (XAS) studies of core level absorptions in nano-crystalline HfO 2 , ZrO 2 and TiO 2 thin films, as well studies of band edge states by photoconductivity and spectroscopic ellipsometry [2][3][4]. The core level XAS transitions terminate in either empty Hf, Zr and Ti d-states for transitions in which the core levels are TM p-states, or molecular orbital states for transitions in which the core level state is the O 1s level.…”
Section: Introductionmentioning
confidence: 99%
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