Tuning thermal conductivity in homoepitaxial SrTiO3 films via defects

Brooks, Charles M.; Wilson, R. B.; Schäfer, A.; Mundy, Julia A.; Holtz, Megan E.; Muller, David A.; Schubert, J.; Cahill, David G.; Schlom, Darrell G.

doi:10.1063/1.4927200

Cited by 39 publications

(39 citation statements)

References 55 publications

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“…[16,49] In addition to alternate surface terminations, fractional step heights can also result from organization of bulk defects into planes or from segregation of a non-stoichiometric surface layer. [30,49,60,61] Figure 4: NC-AFM images illustrating the evolution of the surface morphology of a [100]-oriented SrTiO 3 single crystal sequentially annealed in UHV for 30 minutes to the temperatures indicated in the panels.…”

Section: Evolution Of Surface Morphologymentioning

confidence: 99%

Surface phase, morphology, and charge distribution transitions on vacuum and ambient annealedSrTiO3(100)

et al. 2016

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The surface structures of SrTiO 3 (100) single crystals were examined as a function of annealing time and temperature in either oxygen atmosphere or ultra-high vacuum (UHV) using noncontact atomic force microscopy (NC-AFM), Auger electron spectroscopy (AES), and low-energy electron diffraction (LEED). Samples were subsequently analyzed for the effect the modulation of their charge distribution had on their surface potential. It was found that the evolution of the SrTiO 3 surface roughness, stoichiometry, and reconstruction depends on the preparation scheme. Surface roughness evolved non-monotonically with UHV annealing temperature, which is explained by electrostatic modulations of the surface potential caused by increasing oxygen depletion. This was further corroborated by experiments in which the apparent roughness tracked in NC-AFM could be correlated with changes in the surface charge distribution that were controlled by applying a bias voltage to the sample. Based on these findings, it is suggested that careful selection of preparation procedures combined with application of an electric field may be used to tune the properties of thin films grown on SrTiO 3 .

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Section: Evolution Of Surface Morphologymentioning

confidence: 99%

Surface phase, morphology, and charge distribution transitions on vacuum and ambient annealedSrTiO3(100)

et al. 2016

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“…Besides the different input I-Vs, only two parameters are changed for modeling the different stoichiometries. As the thermal conductivity in STO films decreases with increasing nonstoichiometry, 32,33 be it Ti or Sr excess, we assumed a lower thermal resistance for the temperature-estimation in the stoichiometric film, which results in a lower T disc . The second one is the activation energy for the vacancy hopping DW hop .…”

Section: B Quasi-static Switchingmentioning

confidence: 99%

The influence of non-stoichiometry on the switching kinetics of strontium-titanate ReRAM devices

Fleck

Aslam

Hoffmann‐Eifert

et al. 2016

Journal of Applied Physics

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Vertical power MOS transistor as a thermoelectric quasi-nanowire device J. Appl. Phys. 120, 244903244903 (2016) . The STO films, deposited by atomic layer deposition, were integrated in Pt/STO/TiN nanocrossbars with a feature size of 100 nm. By analysis of the transient currents, the switching kinetics are investigated between 10 ns and 10 4 s for the SET and 10 ns and 100 s for the RESET. A clear influence of the composition on the degree of nonlinearity of the switching kinetics was observed. Applying an analytical model for the oxygen vacancy migration, we were able to explain the differences in the SET kinetics by composition-dependent changes in the thermal conductivity and by a lower activation energy for the Ti-rich sample. This might be utilized in design rules of future ReRAM devices. Published by AIP Publishing. [http://dx

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“…The prototypical perovskite material SrTiO 3 (STO) exhibits a broad variety of functional properties, which might be of interest for future electronic applications such as redox-based memristive devices1, as well as for energy application such as catalysis2 or thermoelectricity3. Although device materials typically require unparalleled levels of purity and perfection, the presence of point and extended defects in SrTiO 3 have been identified to be advantageous for a variety of applications.…”

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confidence: 99%

“…Oxygen vacancies induced by acceptor doping improve the ion conductivity4 and are prerequisite for the operation of redox-based memristive devices1. Cation vacancies, which are common defects in STO thin films5, reduce the thermal conductivity3, the permittivity6 and deteriorate the electron mobility of n-doped STO7. However, it has been reported recently that the formation of Sr vacancy clusters can strongly enhance the electron mobility in Ti rich n-doped STO8.…”

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confidence: 99%

Formation mechanism of Ruddlesden-Popper-type antiphase boundaries during the kinetically limited growth of Sr rich SrTiO3 thin films

Torren

et al. 2016

Sci Rep

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We elucidated the formation process for Ruddlesden-Popper-type defects during pulsed laser deposition of Sr rich SrTiO3 thin films by a combined analysis of in-situ atomic force microscopy, low energy electron diffraction and high resolution scanning transmission electron microscopy. At the early growth stage of 1.5 unit cells, the excess Sr results in the formation of SrO on the surface, resulting in a local termination change from TiO2 to SrO, thereby forming a Sr rich (2 × 2) surface reconstruction. With progressive SrTiO3 growth, islands with thermodynamically stable SrO rock-salt structure are formed, coexisting with TiO2 terminated islands. During the overgrowth of these thermodynamically stable islands, both lateral as well as vertical Ruddlesden-Popper-type anti-phase boundaries are formed, accommodating the Sr excess of the SrTiO3 film. We suggest the formation of thermodynamically stable SrO rock-salt structures as origin for the formation of Ruddlesden-Popper-type antiphase boundaries, which are as a result of kinetic limitations confined to certain regions on the surface.

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Tuning thermal conductivity in homoepitaxial SrTiO3 films via defects

Cited by 39 publications

References 55 publications

Surface phase, morphology, and charge distribution transitions on vacuum and ambient annealedSrTiO3(100)

Surface phase, morphology, and charge distribution transitions on vacuum and ambient annealedSrTiO3(100)

The influence of non-stoichiometry on the switching kinetics of strontium-titanate ReRAM devices

Formation mechanism of Ruddlesden-Popper-type antiphase boundaries during the kinetically limited growth of Sr rich SrTiO3 thin films

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