Critical thickness for giant thermoelectric Seebeck coefficient of 2DEG confined in SrTiO3/SrTi0.8Nb0.2O3 superlattices

Ohta, Hiromichi; Mune, Yoriko; Koumoto, Kunihito; Mizoguchi, Teruyasu; Ikuhara, Yuichi

doi:10.1016/j.tsf.2007.10.034

Cited by 34 publications

(30 citation statements)

References 12 publications

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“…Apart from these studies on typical thin films, thermoelectric properties of other exotic low dimensional structures such as quantum wells, superlattices etc. [108][109][110][111][112][113] were also studied. After the discovery of large thermoelectric power factor in La doped STO, 20 several thin film oriented investigations were performed on doped STO using pulsed laser deposition method.…”

Section: A Titanatesmentioning

confidence: 99%

“…Further studies expanded the phase space over which thermoelectric properties of the Nb:STO/STO superlattice system was studied. 109,170 Recently, Choi et al expanded this line of study by realizing large power factor in fractionally d-doped superlattices of La:STO/STO. 171 Although these studies highlight enhanced thermoelectric properties in dimensionally confined electron gases, further studies are required to identify how can we use such superlattices containing 2DEGs for crafting devices with large thermoelectric efficiency.…”

Section: Size Effects and Low Dimensional Materialsmentioning

confidence: 99%

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Thermoelectric and thermal transport properties of complex oxide thin films, heterostructures and superlattices

Ravichandran

2016

J. Mater. Res.

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Over the years, the search for high performance thermoelectric materials has been dictated by the "phonon glass and electron crystal (PGEC)" paradigm, which suggests that low band gap semiconductors with high atomic number elements and high carrier mobility are the ideal materials to achieve high thermoelectric figure of merit. Complex oxides provide alternative mechanisms such as large density of states and strong electron correlation for high thermoelectric efficiency, albeit having low carrier mobility. Due to vast structural and chemical flexibility, they provide a fertile playground to design high efficiency thermoelectric materials. Further, developments in oxide thin film growth methods have enabled synthesis of high quality, atomically precise low dimensional structures such as heterostructures and superlattices. These materials and structures act as excellent model systems to explore nanoscale thermal and thermoelectric transport, which will not only expand the frontier of our knowledge, but also continue to enable cutting edge applications.

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Section: A Titanatesmentioning

confidence: 99%

Section: Size Effects and Low Dimensional Materialsmentioning

confidence: 99%

Thermoelectric and thermal transport properties of complex oxide thin films, heterostructures and superlattices

Ravichandran

2016

J. Mater. Res.

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“…have been intensively investigated and exhibited many intriguing physical properties including high mobility, 5,16,17 superconductivity, 15,18,19 electric-field controlled resistance, 20 novel magnetism, [21][22][23] and large thermoelectric power. [12][13][14]24 In LAO/STO heterostructures, where both constituents are wide band gap insulators, there exists the critical LAO film thickness of 4 unit cells (u.c.) to become conducting.…”

Section: Introductionmentioning

confidence: 99%

Critical thickness for the two-dimensional electron gas in LaTiO3/SrTiO3superlattices

You

Lee

2013

Phys. Rev. B

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Transport dimensionality of Ti d electrons in (LaTiO 3 ) 1 /(SrTiO 3 ) N superlattices has been investigated using density functional theory with local spin-density approximation + U method. Different spatial distribution patterns have been found between Ti t 2g orbital electrons. The d xy orbital electrons are highly localized near interfaces due to the potentials by positively charged LaO layers, while the degenerate d yz and d xz orbital electrons are more distributed inside SrTiO 3 insulators. For N 3 unit cells (u.c.), the Ti d xy densities of state exhibit the staircaselike increments, which appear at the same energy levels as the d xy flat bands along the -Z direction in band structures. The k z -independent discrete energy levels indicate that the electrons in d xy flat bands are two-dimensional electron gases (2DEGs) which can transport along interfaces, but they cannot transport perpendicularly to interfaces due to the confinements in the potential wells by LaO layers. Unlike the d xy orbital electrons, the d yz and d xz orbital electrons have three-dimensional (3D) transport characteristics, regardless of SrTiO 3 thicknesses. The 2DEG formation by d xy orbital electrons, when N 3 u.c., indicates the existence of critical SrTiO 3 thickness where the electron transport dimensionality starts to change from 3D to 2D in (LaTiO 3 ) 1 /(SrTiO 3 ) N superlattices.

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“…These were selected based on recommendations from several material experts and literatures [6][7][8][9][10]. The expectation was that they will exhibit n-type behavior.…”

Section: Technical Approaches and Schedulementioning

confidence: 99%

High Temperature Integrated Thermoelectric Ststem and Materials

Chu¹

2011

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Critical thickness for giant thermoelectric Seebeck coefficient of 2DEG confined in SrTiO3/SrTi0.8Nb0.2O3 superlattices

Cited by 34 publications

References 12 publications

Thermoelectric and thermal transport properties of complex oxide thin films, heterostructures and superlattices

Thermoelectric and thermal transport properties of complex oxide thin films, heterostructures and superlattices

Critical thickness for the two-dimensional electron gas in LaTiO3/SrTiO3superlattices

High Temperature Integrated Thermoelectric Ststem and Materials

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