Structure and electron affinity of (1 1<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si33.svg"><mml:mrow><mml:mover accent="true"><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover></mml:mrow></mml:math>0)–X 4H–SiC surface

Beattie, J.M.A.; Goss, Jonathan P.; Rayson, Mark; Briddon, P.R.

doi:10.1016/j.apsusc.2020.145986

Cited by 2 publications

(2 citation statements)

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“…The smallest EA is obtained for H-termination on the (0001) face at around 1 eV. These values and their associated ranges would be anticipated and indeed are similar to previous 4H-SiC non-polar terminated surfaces [7] with matching surface coverage and species.…”

Section: Discussionsupporting

confidence: 87%

“…The EA is the energy difference between an electron in vacuum and in the conduction band of a non-metal, so it is affected by the surface, including its chemical termination, with a layer of surface dipoles producing a step up or down in electron-energy, potentially by several volts. We have recently reported the EAs of nonpolar surfaces of 4H-SiC [7], but there is a paucity of data relating to EAs of polar SiC surfaces. This is partly because [15]) results in the charge density peaking closer to the carbon atom.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Structure and electron affinity of the 4H–SiC (0001) surfaces: a methodological approach for polar systems

Beattie

Goss

Rayson

et al. 2021

J. Phys.: Condens. Matter

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The ability to accurately and consistently determine the surface electronic properties of polar materials is of great importance for device applications. Polar surface modelling is fundamentally limited by the spontaneous polarisation of these materials in a periodic boundary condition scheme. Surface data are sensitive to supercell parameters, including slab and vacuum thicknesses, as well as the non-equivalence of surface adsorbates on opposite surfaces. Using 4H-SiC as a specific case, this study explores calculation of electron affinities (EAs) of ( 0001) and ( 0001) surfaces varying chemical termination as a function of computational parameters. We report the impact in terms of band-gap, electric fields across the vacuum and slab for single and double cell slab models, where the latter is constructed with inversional symmetry to eliminate the electric field in the vacuum regions. We find that single cells are sensitive to both slab and vacuum thickness. The band-gap narrows with slab thickness, ultimately vanishing and inducing charge transfer between opposite surfaces. This has a consequence for predicted EAs. Adsorbate species are found to play a crucial role in the rate of narrowing. Back to back cells with inversional symmetry have larger electric fields present across the slab than the single slab cases, resulting in a greater band-gap narrowing effect, but the vacuum thickness dependence is completely removed. We discuss the relative merits of the two approaches.

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Section: Discussionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%