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

We investigate the behavior of holes in the valence band of a range of wide-band-gap oxides including ZnO, MgO, In sub(2) O sub(3), Ga sub(2) O sub(3), Al sub(2) O sub(3), SnO sub(2), SiO sub(2), and TiO sub(2). Based on hybrid functional calculations, we find that, due to the orbital composition of...

Full description

Saved in:
Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2012-02, Vol.85 (8), Article 081109
Main Authors: Varley, J. B., Janotti, A., Franchini, C., Van de Walle, C. G.
Format: Article
Language:English
Subjects:
Condensed matter
Luminescence
Mathematical analysis
Oxides
Polarons
Titanium dioxide
Valence band
Zinc oxide
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We investigate the behavior of holes in the valence band of a range of wide-band-gap oxides including ZnO, MgO, In sub(2) O sub(3), Ga sub(2) O sub(3), Al sub(2) O sub(3), SnO sub(2), SiO sub(2), and TiO sub(2). 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 SiO sub(2). 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.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.85.081109