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Title: Electronic properties of tantalum pentoxide polymorphs from first-principles calculations

Tantalum pentoxide (Ta{sub 2}O{sub 5}) is extensively studied for its attractive properties in dielectric films, anti-reflection coatings, and resistive switching memory. Although various crystalline structures of tantalum pentoxide have been reported, its structural, electronic, and optical properties still remain a subject of research. We investigate the electronic and optical properties of crystalline and amorphous Ta{sub 2}O{sub 5} structures using first-principles calculations based on density functional theory and the GW method. The calculated band gaps of the crystalline structures are too small to explain the experimental measurements, but the amorphous structure exhibits a strong exciton binding energy and an optical band gap (∼4 eV) in agreement with experiment. We determine the atomic orbitals that constitute the conduction band for each polymorph and analyze the dependence of the band gap on the atomic geometry. Our results establish the connection between the underlying structure and the electronic and optical properties of Ta{sub 2}O{sub 5}.
Authors:
 [1] ;  [2] ;  [3] ;  [1]
  1. Department of Materials Science and Engineering, University of Michigan, Ann Arbor 48109 (United States)
  2. (United States)
  3. Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor 48109 (United States)
Publication Date:
OSTI Identifier:
22392011
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 20; 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; BINDING ENERGY; DENSITY FUNCTIONAL METHOD; DIELECTRIC MATERIALS; FILMS; OPTICAL PROPERTIES; REFLECTION; TANTALUM OXIDES