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Journal article 22517 views 246 downloads

Electronic properties of CaF2 bulk and interfaces

Jiaqi Chen, Zhaofu Zhang Orcid Logo, Yuzheng Guo Orcid Logo, John Robertson Orcid Logo

Journal of Applied Physics, Volume: 131, Issue: 21, Start page: 215302

Swansea University Author: Yuzheng Guo Orcid Logo

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DOI (Published version): 10.1063/5.0087914

Abstract

The electronic band structures of ultra-wide gap CaF2 are investigated with both the hybrid functional and the efficient generalized gradient approximation (GGA) + U scheme. The hybrid functional scheme is in excellent agreement with experiments, while introducing an on-site Coulomb interaction to F...

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Published in: Journal of Applied Physics
ISSN: 0021-8979 1089-7550
Published: AIP Publishing 2022
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa60253
Abstract: The electronic band structures of ultra-wide gap CaF2 are investigated with both the hybrid functional and the efficient generalized gradient approximation (GGA) + U scheme. The hybrid functional scheme is in excellent agreement with experiments, while introducing an on-site Coulomb interaction to F-2p orbitals also accurately reproduces the experimental bandgap and greatly improves the previous theoretical results using advanced electronic structure schemes. We also apply the GGA + U method to study CaF2/Si and metal/CaF2 interfaces. The CaF2/Si insulating interfaces with a clear bandgap are built based on the electron counting rule. Our supercell calculations of the CaF2/Si interfaces show a type-II band alignment and the valence band offset follows a descending trend from (001) to (111) then to (110). The calculation convergence of GGA + U is further tested with the metallic contacts. The metal/CaF2 interfaces are observed to be weakly pinned and different orientations of CaF2 sharing a similar pinning factor S up to ∼0.9, owing to the highly ionic nature of CaF2. The GGA + U approach is proven to be a useful tool in studying such fluoride interfaces and contacts.
Item Description: Data availability: The data that support the findings of this study are available from the corresponding author upon reasonable request.
College: Faculty of Science and Engineering
Funders: The authors acknowledge funding from EPSRC under Grant No. EP/P005152/1. We also thank support from Cambridge CSD3 Supercomputing under Project No. CS129 and Supercomputing Wales under Project No. SCW1070.
Issue: 21
Start Page: 215302

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