Abstract
In recent years it has been proved possible to predict the valence-band offsets of lattice-matched semiconductor heterojunctions1,2 to an accuracy of about 0.1 eV using density functional theory in the local approximation (LDA). We have investigated whether, for well-characterised metal-semiconductor interfaces, the Schottky-barrier heights can be calculated with similar accuracy. In this paper we report on our findings.
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References
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We have also performed some calculations with a basis of , s-, p- and d-LMTOs on all atomic and empty sites. This reduces the bulk values of E-g, and E° by about 0.2 eV. But the zeroth order band offset = - E°, as well as the interface dipole remain unchanged.
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The fact that our estimate of Ep—Ey for the B—interface is now negative, and apparently unphysical, does not mean that the supercell charge density has holes in the valence band, but simply that the energy of the highest valence-band state of the (8+6)-supercell lies below Ey for the semi-infinite system, and below Ep. In terms of the thickness L = 5.9 a0 m of the’m’-layer Si-slab of the supercell (in our case m = 6 ), an estimate of this energy-lowering due to confinement is (7r/L)2 Ry « 0.1 eV. The order of magnitude is thus reasonable.
This correction amounts essentially to shifting the energies, C, of the Si and E s-orbitals upwards by respectively 0.22 and 1.88 eV.
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© 1989 Plenum Press, New York
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Das, G.P., Blöchl, P., Christensen, N.E., Andersen, O.K. (1989). Calculated Electronic Structures and Schottky Barrier Heights of (111) NiSi2/Si A- and B-Type Interfaces. In: Batra, I.P. (eds) Metallization and Metal-Semiconductor Interfaces. NATO ASI Series, vol 195. Springer, Boston, MA. https://doi.org/10.1007/978-1-4613-0795-2_13
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DOI: https://doi.org/10.1007/978-1-4613-0795-2_13
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