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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
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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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