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arXiv · 1505.02859

Polaron transport and thermoelectric behavior in La-doped SrTiO3 thin films with elemental vacancies

Woo Seok Choi·Hyang Keun Yoo·Hiromichi Ohta
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Abstract

Electrodynamic properties of La-doped SrTiO3 thin films with controlled elemental vacancies have been investigated using optical spectroscopy and thermopower measurement. In particular, we observed a correlation between the polaron formation and thermoelectric properties of the transition metal oxide (TMO) thin films. With decreasing oxygen partial pressure during the film growth (P(O2)), a systematic lattice expansion was observed along with the increased elemental vacancy and carrier density, experimentally determined using optical spectroscopy. Moreover, we observed an absorption in the mid-infrared photon energy range, which is attributed to the polaron formation in the doped SrTiO3 system. Thermopower of the La-doped SrTiO3 thin films could be largely modulated from -120 to -260 {\mu}V K-1, reflecting an enhanced polaronic mass of ~3 < mpolron/m < ~4. The elemental vacancies generated in the TMO films grown at various P(O2) influences the global polaronic transport, which governs the charge transport behavior, including the thermoelectric properties.

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Woo Seok Choi, Hyang Keun Yoo, Hiromichi Ohta. 2015-05-12. Polaron transport and thermoelectric behavior in La-doped SrTiO3 thin films with elemental vacancies. https://doi.org/10.1002/adfm.201403023

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