La-doped SrTiO3 films with large cryogenic thermoelectric power factors

Cain, Tyler A.; Kajdos, Adam P.; Stemmer, Susanne

doi:10.1063/1.4804182

Cited by 91 publications

(107 citation statements)

References 31 publications

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“…For this purpose, the extrapolation of the experimental data was based on the recent work of La-doped STO films grown by hybrid molecular beam epitaxy, conducted by Cain and co-workers. 68 Their samples have relatively higher electrical conductivities at the same conditions (T and n) compared to other studies, which may indicate the higher quality of the STO films. Specifically, we used the data set which has the highest σ and chose the experimental S at corresponding T with a value of about −270 µV/K at 300 K. The reason is that we want to estimate the optimum ZT, and the choice of the best samples as the baseline minimizes the effects on the predicted ZT due to extrinsic effects that are presumably controllable.…”

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confidence: 63%

Thermoelectric properties of n-type SrTiO3

Sun

Singh

2016

APL Materials

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We present an investigation of the thermoelectric properties of cubic perovskite SrTiO3. The results are derived from a combination of calculated transport functions obtained from Boltzmann transport theory in the constant scattering time approximation based on the electronic structure and existing experimental data for La-doped SrTiO3. The figure of merit ZT is modeled with respect to carrier concentration and temperature. The model predicts a relatively high ZT at optimized doping and suggests that the ZT value can reach 0.7 at T = 1400 K. Thus ZT can be improved from the current experimental values by carrier concentration optimization.

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confidence: 63%

Thermoelectric properties of n-type SrTiO3

Sun

Singh

2016

APL Materials

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“…117 Other growth techniques such as sputtering, 118 and molecular beam epitaxy (MBE) 119 were successfully used to grow doped STO films. Especially, MBE grown films demonstrated large cryogenic thermopower due to the phonon drag effect, 120 due to exquisite stoichiometry control. The thermal properties of undoped STO were studied using a variety of growth methods to verify the ability of each technique in producing high quality STO films.…”

Section: A Titanatesmentioning

confidence: 99%

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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“…The growth conditions that give optimal stoichiometry can be identified by the overlap of the XRD growth window with the c(4×4) regime. La-doped SrTiO 3 films with the highest recorded electron mobilities for unstrained films, exceeding 50,000 cm 2 V -1 s -1 were grown in this regime [27].…”

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confidence: 98%

Surface reconstructions in molecular beam epitaxy of SrTiO3

Kajdos

Stemmer

2014

Applied Physics Letters

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We show that reflection high-energy electron diffraction (RHEED) can be used as a highly sensitive tool to track surface and resulting film stoichiometry in adsorption-limited molecular beam epitaxy of (001) SrTiO 3 thin films. Even under growth conditions that yield films with a lattice parameter that is identical to that of stoichiometric bulk crystals within the detection limit of high-resolution x-ray diffraction (XRD), changes in surface reconstruction occur from (1×1) to (2×1) to c(4×4) as the equivalent beam pressure of the Ti metalorganic source is increased.These surface reconstructions are correlated with a shift from mixed SrO/TiO 2 termination to pure TiO 2 termination. The crossover to TiO 2 surface termination is also apparent in a phase shift in RHEED oscillations observed at the beginning of growth. Comparison with prior results for carrier mobilities of doped films shows that the best films are grown under conditions of a TiO 2 -saturated surface [c(4×4) reconstruction] within the XRD growth window.

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La-doped SrTiO3 films with large cryogenic thermoelectric power factors

Cited by 91 publications

References 31 publications

Thermoelectric properties of n-type SrTiO3

Thermoelectric properties of n-type SrTiO3

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

Surface reconstructions in molecular beam epitaxy of SrTiO3

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