Two-dimensional electron gas in the KNbO3:Y ultrathin film
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First-principles calculations are used to study KNbO3:Y ultrathin film. The conducting two-dimensional electron gas (2DEG) is found in KNbO3:Y film, whereas SrTiO3:Y superlattice is insulating [Science 331, 886 (2011)]. The carrier density of 2DEG of KNbO3:Y film is twice that of LaTiO3/SrTiO3 superlattice, which is in agreement with the theoretical results of KNbO3:La superlattice. It is found that the charge densities of different monolayers are modulated by the polarization effect of KNbO3. We predict that 2DEG may be in other rare-earth atoms-doped KNbO3 film.
KeywordsUltrathin Film Ferroelectric Polarization Fermi Energy Level KNbO3 Parabolic Energy Band
The research is supported by National Natural Science Foundation of China (Nos.11204053 and 11074059) and the China Postdoctoral Science Foundation (Grant No. 2013M531028). We would like to thank High Performance Computing Center of Harbin Institute of Technology for the help of the calculation.
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