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Role of self-trapping in luminescence and p-type conductivity of wide-band-gap oxides

Autor(en)
Cesare Franchini, Anderson Janotti, Joel B. Varley, Chris G. Van de Walle
Abstrakt

We investigate the behavior of holes in the valence band of a range of wide-band-gap oxides including ZnO, MgO, In2O3, Ga2O3, Al2O3, SnO2, SiO2, and TiO2. Based on hybrid functional calculations, we find that, due to the orbital composition of the valence band, holes tend to form localized small polarons with characteristic lattice distortions, even in the absence of defects or impurities. These self-trapped holes (STHs) are energetically more favorable than delocalized, free holes in the valence band in all materials but ZnO and SiO2. Based on calculated optical absorption and emission energies we show that STHs provide an explanation for the luminescence peaks that have been observed in many of these oxides. We demonstrate that polaron formation prohibits p-type conductivity in this class of materials.

Organisation(en)
Computergestützte Materialphysik
Externe Organisation(en)
University of California, Santa Barbara
Journal
Physical Review B
Band
85
Anzahl der Seiten
4
ISSN
1098-0121
DOI
https://doi.org/10.1103/PhysRevB.85.081109
Publikationsdatum
2012
Peer-reviewed
Ja
ÖFOS 2012
103009 Festkörperphysik, 103015 Kondensierte Materie, 103025 Quantenmechanik, 103036 Theoretische Physik
Link zum Portal
https://ucrisportal.univie.ac.at/de/publications/427008c7-6b2d-4288-bdd5-d8bb2c46443b