Electronic and optical properties of the cubic spinel phase of c-Si{sub 3}N{sub 4}, c-Ge{sub 3}N{sub 4}, c-SiGe{sub 2}N{sub 4}, and c-GeSi{sub 2}N{sub 4}
The electronic and optical properties of the new cubic spinel nitrides c-Si{sub 3}N{sub 4}, c-Ge{sub 3}N{sub 4}, and that of the predicted double nitrides c-SiGe{sub 2}N{sub 4} and c-GeSi{sub 2}N{sub 4} are studied by a first-principles method. They are all semiconductors with band gaps between 1.85 and 3.45 eV and a bulk modulus between 258 and 280 GPa. From the total-energy calculations, it is shown that c-SiGe{sub 2}N{sub 4} should be a stable compound while c-GeSi{sub 2}N{sub 4} could be metastable. The compound c-SiGe{sub 2}N{sub 4} is of particular interest because of a favorable direct band gap of 1.85 eV and a conduction-band effective mass of 0.49. The crystal has a very strong covalent bonding character as revealed by the calculated Mulliken effective charge and bond order. The strong covalent bonding in c-SiGe{sub 2}N{sub 4} is attributed to the optimal arrangement of the cations. The smaller Si ion occupies the tetrahedrally coordinated (8a) site and the larger Ge ion occupies the octahedrally coordinated (16d) site.
- Research Organization:
- Univ. of Missouri, Columbia, MO (United States)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- FG02-84ER45170
- OSTI ID:
- 40277780
- Journal Information:
- Physical Review B, Vol. 63, Issue 24; Other Information: DOI: 10.1103/PhysRevB.63.245110; Othernumber: PRBMDO000063000024245110000001; 061124PRB; PBD: 15 Jun 2001; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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