Enhanced Seebeck coefficient of quantum-confined electrons in SrTiO_3/SrTi_0.8Nb_0.2O_3 superlattices
Abstract
We report two-dimensional Seebeck coefficients (|S|_2D) of [(SrTiO_3)x/(SrTi_0.8Nb_0.2O_3)y]_20 (x=1–60, y=1–20) superlattices, which were grown on the (100) face of insulating LaAlO_3 substrates to clarify the origin of the giant |S|_2D values of the SrTiO_3 superlattices [H. Ohta et al., Nat. Mater. 6, 129 (2007)]. The |S|_2D values of the [(SrTiO_3)_17/(SrTi_0.8Nb_0.2O_3)y]_20 superlattices increased proportionally to y^{−0.5} and reached 320µVK^{−1} (y=1), which is approximately five times larger than that of the SrTi_0.8Nb_0.2O_3 bulk (|S|_3D=61µVK^{−1}). The slope of the log|S|_2D-log y plots was −0.5, proving that the density of states in the ground state for SrTiO_3 increases inversely proportionally to y. The critical barrier thickness for quantum electron confinement was also clarified to be 6.25nm (16 unit cells of SrTiO_3).
Journal
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- APPLIED PHYSICS LETTERS
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APPLIED PHYSICS LETTERS 91 192105-192105, 2007-11-08
American Institite of Physics
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Details 詳細情報について
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- CRID
- 1050001338798130560
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- NII Article ID
- 120001442811
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- HANDLE
- 2237/11980
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- ISSN
- 00036951
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- Text Lang
- en
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- Article Type
- journal article
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- Data Source
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- IRDB
- CiNii Articles