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Title: Evidence for anisotropic dielectric properties of monoclinic hafnia using valence electron energy-loss spectroscopy in high-resolution transmission electron microscopy and ab initio time-dependent density-functional theory

The effect of nanocrystal orientation on the energy loss spectra of monoclinic hafnia (m-HfO{sub 2}) is measured by high resolution transmission electron microscopy (HRTEM) and valence energy loss spectroscopy (VEELS) on high quality samples. For the same momentum-transfer directions, the dielectric properties are also calculated ab initio by time-dependent density-functional theory (TDDFT). Experiments and simulations evidence anisotropy in the dielectric properties of m-HfO{sub 2}, most notably with the direction-dependent oscillator strength of the main bulk plasmon. The anisotropic nature of m-HfO{sub 2} may contribute to the differences among VEELS spectra reported in literature. The good agreement between the complex dielectric permittivity extracted from VEELS with nanometer spatial resolution, TDDFT modeling, and past literature demonstrates that the present HRTEM-VEELS device-oriented methodology is a possible solution to the difficult nanocharacterization challenges given in the International Technology Roadmap for Semiconductors.
Authors:
 [1] ;  [2] ; ;  [3] ;  [4] ;  [5] ;  [1] ;  [2] ;  [4] ;  [1] ;  [4] ;  [2]
  1. University Grenoble Alpes, F-38000 Grenoble (France)
  2. (France)
  3. LSI, CNRS, CEA, École Polytechnique, F-91128 Palaiseau (France)
  4. (ETSF) (France)
  5. LPS, CNRS and University Paris Sud, F-91405 Orsay (France)
Publication Date:
OSTI Identifier:
22402421
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 22; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DENSITY FUNCTIONAL METHOD; DIELECTRIC MATERIALS; ENERGY-LOSS SPECTROSCOPY; HAFNIUM OXIDES; MOMENTUM TRANSFER; MONOCLINIC LATTICES; NANOSTRUCTURES; OSCILLATOR STRENGTHS; PERMITTIVITY; SEMICONDUCTOR MATERIALS; SIMULATION; TIME DEPENDENCE; TRANSMISSION ELECTRON MICROSCOPY