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Bistability of Hydrogen in ZnO: Origin of Doping Limit and Persistent Photoconductivity
Substitutional hydrogen at oxygen site (H(O)) is well-known to be a robust source of n-type conductivity in ZnO, but a puzzling aspect is that the doping limit by hydrogen is only about 10(18) cm(−3), even if solubility limit is much higher. Another puzzling aspect of ZnO is persistent photoconducti...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group
2014
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3927214/ https://www.ncbi.nlm.nih.gov/pubmed/24535157 http://dx.doi.org/10.1038/srep04124 |
Sumario: | Substitutional hydrogen at oxygen site (H(O)) is well-known to be a robust source of n-type conductivity in ZnO, but a puzzling aspect is that the doping limit by hydrogen is only about 10(18) cm(−3), even if solubility limit is much higher. Another puzzling aspect of ZnO is persistent photoconductivity, which prevents the wide applications of the ZnO-based thin film transistor. Up to now, there is no satisfactory theory about two puzzles. We report the bistability of H(O) in ZnO through first-principles electronic structure calculations. We find that as Fermi level is close to conduction bands, the H(O) can undergo a large lattice relaxation, through which a deep level can be induced, capturing electrons and the deep state can be transformed into shallow donor state by a photon absorption. We suggest that the bistability can give explanations to two puzzling aspects. |
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