Electronic structure of the alkaline-earth silicon nitrides M2Si5N8 (M = Ca and Sr) obtained from first-principles calculations and optical reflectance spectra

C.M. Fang, H.T.J.M. Hintzen, G. With, de, R.A. Groot, de

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Abstract

Results of first-principles band-structure calculations for the ternary alkaline-earth silicon nitrides M2Si5N8 (M = Ca and Sr) are presented. In the structures of M2Si5N8 (M = Ca, Sr and Ba), the N atoms show connections to two (N[2]) and three (N[3]) neighbouring silicon tetrahedral centres. Calculations show that the local electronic structure is strongly dependent on the local chemical bonding. The valence band is dominated by N 2p hybridized with the s, p states of the alkaline-earth-metal and silicon atoms. The upper part of the valence band is dominated by the 2p states of N[2] atoms, while the N[3] 2p states lie about 2 eV below the Fermi level. The bottom of the conduction band consists of the N 3s characters hybridized with s orbitals of the alkaline-earth metals, while the s character of Si atoms is higher in energy. Sr2Si5N8 is a semiconductor with a direct energy gap at G, while Ca2Si5N8 is an indirect semiconductor. Optical diffuse reflectance spectra show an energy gap of 4.9 eV for Ca2Si5N8, 4.5 eV for Sr2Si5N8, as well as 4.1 eV for Ba2Si5N8, in fair agreement with the calculated values.
Original languageEnglish
Pages (from-to)67-76
JournalJournal of Physics : Condensed Matter
Volume13
Issue number1
DOIs
Publication statusPublished - 2001

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Silicon nitride
silicon nitrides
Electronic structure
Earth (planet)
Alkaline Earth Metals
electronic structure
reflectance
Alkaline earth metals
Atoms
alkaline earth metals
Silicon
Valence bands
atoms
Energy gap
Semiconductor materials
valence
silicon
Fermi level
Conduction bands
Band structure

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@article{f7e8f7a5d05d4c038cac564920b60668,
title = "Electronic structure of the alkaline-earth silicon nitrides M2Si5N8 (M = Ca and Sr) obtained from first-principles calculations and optical reflectance spectra",
abstract = "Results of first-principles band-structure calculations for the ternary alkaline-earth silicon nitrides M2Si5N8 (M = Ca and Sr) are presented. In the structures of M2Si5N8 (M = Ca, Sr and Ba), the N atoms show connections to two (N[2]) and three (N[3]) neighbouring silicon tetrahedral centres. Calculations show that the local electronic structure is strongly dependent on the local chemical bonding. The valence band is dominated by N 2p hybridized with the s, p states of the alkaline-earth-metal and silicon atoms. The upper part of the valence band is dominated by the 2p states of N[2] atoms, while the N[3] 2p states lie about 2 eV below the Fermi level. The bottom of the conduction band consists of the N 3s characters hybridized with s orbitals of the alkaline-earth metals, while the s character of Si atoms is higher in energy. Sr2Si5N8 is a semiconductor with a direct energy gap at G, while Ca2Si5N8 is an indirect semiconductor. Optical diffuse reflectance spectra show an energy gap of 4.9 eV for Ca2Si5N8, 4.5 eV for Sr2Si5N8, as well as 4.1 eV for Ba2Si5N8, in fair agreement with the calculated values.",
author = "C.M. Fang and H.T.J.M. Hintzen and {With, de}, G. and {Groot, de}, R.A.",
year = "2001",
doi = "10.1088/0953-8984/13/1/307",
language = "English",
volume = "13",
pages = "67--76",
journal = "Journal of Physics : Condensed Matter",
issn = "0953-8984",
publisher = "Institute of Physics",
number = "1",

}

Electronic structure of the alkaline-earth silicon nitrides M2Si5N8 (M = Ca and Sr) obtained from first-principles calculations and optical reflectance spectra. / Fang, C.M.; Hintzen, H.T.J.M.; With, de, G.; Groot, de, R.A.

In: Journal of Physics : Condensed Matter, Vol. 13, No. 1, 2001, p. 67-76.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Electronic structure of the alkaline-earth silicon nitrides M2Si5N8 (M = Ca and Sr) obtained from first-principles calculations and optical reflectance spectra

AU - Fang, C.M.

AU - Hintzen, H.T.J.M.

AU - With, de, G.

AU - Groot, de, R.A.

PY - 2001

Y1 - 2001

N2 - Results of first-principles band-structure calculations for the ternary alkaline-earth silicon nitrides M2Si5N8 (M = Ca and Sr) are presented. In the structures of M2Si5N8 (M = Ca, Sr and Ba), the N atoms show connections to two (N[2]) and three (N[3]) neighbouring silicon tetrahedral centres. Calculations show that the local electronic structure is strongly dependent on the local chemical bonding. The valence band is dominated by N 2p hybridized with the s, p states of the alkaline-earth-metal and silicon atoms. The upper part of the valence band is dominated by the 2p states of N[2] atoms, while the N[3] 2p states lie about 2 eV below the Fermi level. The bottom of the conduction band consists of the N 3s characters hybridized with s orbitals of the alkaline-earth metals, while the s character of Si atoms is higher in energy. Sr2Si5N8 is a semiconductor with a direct energy gap at G, while Ca2Si5N8 is an indirect semiconductor. Optical diffuse reflectance spectra show an energy gap of 4.9 eV for Ca2Si5N8, 4.5 eV for Sr2Si5N8, as well as 4.1 eV for Ba2Si5N8, in fair agreement with the calculated values.

AB - Results of first-principles band-structure calculations for the ternary alkaline-earth silicon nitrides M2Si5N8 (M = Ca and Sr) are presented. In the structures of M2Si5N8 (M = Ca, Sr and Ba), the N atoms show connections to two (N[2]) and three (N[3]) neighbouring silicon tetrahedral centres. Calculations show that the local electronic structure is strongly dependent on the local chemical bonding. The valence band is dominated by N 2p hybridized with the s, p states of the alkaline-earth-metal and silicon atoms. The upper part of the valence band is dominated by the 2p states of N[2] atoms, while the N[3] 2p states lie about 2 eV below the Fermi level. The bottom of the conduction band consists of the N 3s characters hybridized with s orbitals of the alkaline-earth metals, while the s character of Si atoms is higher in energy. Sr2Si5N8 is a semiconductor with a direct energy gap at G, while Ca2Si5N8 is an indirect semiconductor. Optical diffuse reflectance spectra show an energy gap of 4.9 eV for Ca2Si5N8, 4.5 eV for Sr2Si5N8, as well as 4.1 eV for Ba2Si5N8, in fair agreement with the calculated values.

U2 - 10.1088/0953-8984/13/1/307

DO - 10.1088/0953-8984/13/1/307

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EP - 76

JO - Journal of Physics : Condensed Matter

JF - Journal of Physics : Condensed Matter

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