Wide-voltage-window reversible control of electronic transport in electrolyte-gated epitaxial ${\mathrm{BaSnO}}_3$

Journal Article · 02 July 2019 · Physical Review Materials

DOI: https://doi.org/10.1103/PhysRevMaterials.3.075001 · OSTI ID:1573496

Wang, Helin ^[1]; Walter, Jeff ^[1]; Ganguly, Koustav ^[1]; Yu, Biqiong ^[1]; Yu, Guichuan ^[1]; Zhang, Zhan ^[2]; Zhou, Hua ^[2]; Fu, Han ^[3]; Greven, Martin ^[1]; Leighton, Chris  ^[1]

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1. Univ. of Minnesota, Minneapolis, MN (United States)
2. Argonne National Lab. (ANL), Argonne, IL (United States)
3. Univ. of Minnesota, Minneapolis, MN (United States); Univ. of Chicago, IL (United States). James Franck Inst.

The wide gap perovskite semiconductor BaSnO₃ has attracted much interest since the discovery of room temperature electron mobility up to 320 cm² V^-1 s^-1 in bulk crystals. Motivated by applications in oxide heterostructures, rapid progress has been made with BaSnO₃ films, although questions remain regarding transport mechanisms and mobility optimization. Here we report on a detailed study of epitaxial BaSnO₃ electric double layer transistors based on ion gel electrolytes, enabling wide-doping-range studies of transport in single films. The work spans an order of magnitude in initial n doping (similar to 10¹⁹ to 10²⁰ cm^-3, with both oxygen vacancies and La), film thicknesses from 10-50 nm, and measurements of resistance, Hall effect, mobility, and magnetoresistance. In contrast with many oxides, electrolyte gating of BaSnO₃ is found to be essentially reversible over an exceptional gate voltage window (approaching +/- 4 V), even at 300 K, supported by negligible structural modification in operando synchrotron x-ray diffraction. We propose that this occurs due to a special situation in BaSnO3, where electrochemical gating via oxygen vacancies is severely limited by their low diffusivity. Wide-range reversible modulation of transport is thus achieved (in both electron accumulation and depletion modes), spanning strongly localized, weakly localized, and metallic regimes. Two-channel conduction analysis is then combined with self-consistent Schrodinger-Poisson and Thomas-Fermi modeling to extract accumulation layer electron densities and mobilities. Electrostatic electron densities approaching 10¹⁴ cm^-2 are shown to increase room temperature mobility by up to a factor of similar to 24. These results lay the groundwork for future studies of electron-density-dependent phenomena in high mobility BaSnO₃, and significantly elucidate oxide electrolyte gating mechanisms.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1573496
• Alternate ID(s): OSTI ID: 1530638
• Journal Information: Physical Review Materials, Vol. 3, Issue 7; ISSN 2475-9953
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English