Limitations to the room temperature mobility of two- and three-dimensional electron liquids in SrTiO3

Mikheev, Evgeny; Himmetoḡlu, Burak; Kajdos, Adam P.; Moetakef, Pouya; Cain, Tyler A.; Walle, Chris G. Van de; Stemmer, Susanne

doi:10.1063/1.4907888

Cited by 63 publications

(87 citation statements)

References 36 publications

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“…The contribution of the carrier mobility change is typically < 10% of the total conductivity change, as the mobility at these temperatures is limited by optical phonon scattering with only a moderate dependence on the electron density. [23] For a-LAO/STO the maximum carrier density is typically around 10 14 cm -2 at room temperature [19] , whereas for GAO/STO carrier densities up to 10 15 cm -2 have been reported. [17] In both cases, the carrier density can easily be controlled without sample-to-sample variations in a large range from the maximum value to a level where the free carriers cannot be measured.…”

Section: Resultsmentioning

confidence: 99%

Controlling the Carrier Density of SrTiO₃‐Based Heterostructures with Annealing

Christensen

Soosten

Trier

et al. 2017

Adv Elect Materials

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Abstract:The conducting interface between the insulating oxides LaAlO3 (LAO) and SrTiO3 (STO) displays numerous physical phenomena that can be tuned by varying the carrier density, which is generally achieved by electrostatic gating or adjustment of growth parameters. Here, we report how annealing in oxygen at low temperatures ( < 300 ℃) can be used as a simple route to control the carrier density by several orders of magnitude. The pathway to control the carrier density relies on donor oxidation and is thus applicable to material systems where oxygen vacancies are the dominant source of conductivity. Using STO capped with epitaxial γ-Al2O3 (GAO) or amorphous LAO (a-LAO), we identify the pathways for changing the carrier density in the two STO-based cases where oxygen blocking (GAO) and oxygen permeable (a-LAO) films create interface conductivity from oxygen vacancies located in STO near the interface. For a-LAO/STO, the rate limiting step ( = 0.25 eV) for oxidizing oxygen vacancies is the transportation of oxygen from the atmosphere through the a-LAO film, whereas GAO/STO is limited by oxygen migration inside STO ( = 0.5 eV). Finally, we show how the control of the carrier density enables writing of conducting nanostructures in γ-Al2O3/STO by conducting atomic force microscopy (c-AFM).

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Section: Resultsmentioning

confidence: 99%

Controlling the Carrier Density of SrTiO₃‐Based Heterostructures with Annealing

Christensen

Soosten

Trier

et al. 2017

Adv Elect Materials

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“…While the resistivities of typical heavily-doped semiconductors and metals are proportional to temperature, [22,23] the resistivities of many perovskite oxides (SrTiO 3 , [24][25][26] SrMoO 3 , [27] KTaO 3 , [28] SrNbO 3 , [29] and SrCoO 3 ) [30] are proportional to temperature-squared (T 2 ). While the resistivities of typical heavily-doped semiconductors and metals are proportional to temperature, [22,23] the resistivities of many perovskite oxides (SrTiO 3 , [24][25][26] SrMoO 3 , [27] KTaO 3 , [28] SrNbO 3 , [29] and SrCoO 3 ) [30] are proportional to temperature-squared (T 2 ).…”

Section: Introductionmentioning

confidence: 99%

Effect of Two‐Dimensional Crystal Orbitals on Fermi Surfaces and Electron Transport in Three‐Dimensional Perovskite Oxides

2019

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Perovskite oxides are candidate materials in catalysis, fuel cells, thermoelectrics, and electronics, where electronic transport is vital to their use. While the fundamental transport properties of these materials have been heavily studied, there are still key features that are not well understood, including the temperature‐squared behavior of their resistivities. Standard transport models fail to account for this atypical property because Fermi surfaces of many perovskite oxides are low‐dimensional and distinct from traditional semiconductors. In this work, the low‐dimensional Fermi surfaces of perovskite oxides are chemically interpreted in terms of two‐dimensional crystal orbitals that form the conduction bands. Using SrTiO3 as a case study, the d/p‐hybridization that creates these low‐dimensional electronic structures is reviewed and connected to its fundamentally different electronic properties. A low‐dimensional band model explains several experimental transport properties, including the temperature and carrier‐density dependence of the effective mass, the carrier‐density dependence of scattering, and the temperature dependence of resistivity. This work highlights how chemical bonding influences semiconductor transport.

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“…Unfortunately, the low electron mobility of STO at room temperature (and higher temperatures) is largely due to strong electron-phonon coupling, which is the primary limitation for further increasing power factor at room temperatures or higher. [51][52][53][54][55] Besides high effective mass, enhanced scattering rates of electrons (e.g., with phonons) is another reason for low mobility in such large density of states materials.…”

Section: àmentioning

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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Limitations to the room temperature mobility of two- and three-dimensional electron liquids in SrTiO3

Cited by 63 publications

References 36 publications

Controlling the Carrier Density of SrTiO₃‐Based Heterostructures with Annealing

Controlling the Carrier Density of SrTiO₃‐Based Heterostructures with Annealing

Effect of Two‐Dimensional Crystal Orbitals on Fermi Surfaces and Electron Transport in Three‐Dimensional Perovskite Oxides

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

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Limitations to the room temperature mobility of two- and three-dimensional electron liquids in SrTiO3

Cited by 63 publications

References 36 publications

Controlling the Carrier Density of SrTiO3‐Based Heterostructures with Annealing

Controlling the Carrier Density of SrTiO3‐Based Heterostructures with Annealing

Effect of Two‐Dimensional Crystal Orbitals on Fermi Surfaces and Electron Transport in Three‐Dimensional Perovskite Oxides

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

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Controlling the Carrier Density of SrTiO₃‐Based Heterostructures with Annealing

Controlling the Carrier Density of SrTiO₃‐Based Heterostructures with Annealing