科研之友
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摘要
Using hybrid density functional theory, we investigate the impact of native vacancies and hydrogen impurities on the electrical and optical properties of cubic SrZrO3. Oxygen vacancies (V-O) form localized states and introduce deep donor levels in the gap. The formation energy of V-O is low when the Fermi level is near the valence band; V-O will thus be a compensating center in acceptor-doped SrZrO3. Sr and Zr vacancies (V-Sr/V-Zr) are acceptor-type defects, and have low formations energies when the Fermi level is near the conduction band. Hole localization on oxygen dangling bonds is an important feature of these vacancies. V-Sr is most prevalent and can account for the luminescence peak at 3.4 eV observed in Sr-deficient SrZrO3. Hydrogen impurities are found to preferentially incorporate at an interstitial site (H-i), forming an O-H bond and acting as a donor. H-i can also be stabilized as an acceptor, sitting midway between adjacent Sr atoms; the epsilon(+/-) transition level is found at 0.44 eV below the conduction band. Hydrogen can also substitute on an oxygen site (H-O), acting as a shallow donor. The formation energy of H-O is high compared to H-i, yet it is stable with respect to dissociation into H-i and V-O.
- 出版日期2014-5-22
