| Texto completo | |
| Autor(es): |
Sabino, Fernando P.
;
Oliveira, Luiz N.
;
Wei, Su-Huai
;
Da Silva, Juarez L. F.
Número total de Autores: 4
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Journal of Applied Physics; v. 123, n. 5, p. 9-pg., 2018-02-07. |
| Resumo | |
Transparent conducting oxides such as the bixbyite In2O3 and rutile SnO2 systems have large disparities between the optical and fundamental bandgaps, Delta E-g(OF), because selection rules forbid dipolar transitions from the top of the valence band to the conduction-band minimum; however, the optical gaps of multi-cation compounds with the same chemical species often coincide with their fundamental gaps. To explain this conundrum, we have employed density-functional theory to compute the optical properties of multi-cation compounds, In2ZnO4 and In4Sn3O12, in several crystal structures. We show that a recently proposed mechanism to explain the disparity between the optical and fundamental gaps of M2O3 (M = Al, Ga, and In) applies also to other binary systems and to multi-compounds. Namely, a gap disparity will arise if the following three conditions are satisfied: (i) the crystal structure has inversion symmetry; (ii) the conduction-band minimum is formed by the cation and O s-orbitals; and (iii) there is strong p-d coupling and weak p-p in the vicinity of the valence-band maximum. The third property depends critically on the cationic chemical species. In the structures with inversion symmetry, Zn (Sn) strengthens (weakens) the p-d coupling in In2ZnO4 (In4Sn3O12), enhancing (reducing) the gap disparity. Furthermore, we have also identified a In4Sn3O12 structure that is 31.80 meV per formula unit more stable than a recently proposed alternative model. Published by AIP Publishing. (AU) | |
| Processo FAPESP: | 13/21045-2 - Predição teórica da estrutura, estabilidade termodinâmica, propriedades electronicas e reatividade de nanoclusters |
| Beneficiário: | Juarez Lopes Ferreira da Silva |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |