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The wide-gap semiconducting perovskite BaSnO3 has attracted attention since the discovery of outstanding mobility at high electron densities, spurred on by potential applications in oxide, transparent, and power electronics. Despite progress, much remains to be understood in terms of mobility-limiting scattering in BaSnO3 thin films and thus mobility optimization. Here, we apply solid-state ion-gel-based electrolyte gating to electrostatically control electron density over a wide range (1018 cm-3 to >1020 cm-3) in BaSnO3 films. Temperature- and gate-voltage-dependent transport data then probe scattering mechanisms and mobility vs electron density alone, independently of sample-to-sample defect density variations. This is done on molecular-beam-epitaxy- and sputter-deposited films as a function of thickness, initial chemical doping, and initial mobility. Remarkably universal behavior occurs, the mobility first increasing with electron density to ∼1020 cm-3 before decreasing slightly. This trend is quantitatively analyzed at cryogenic and room temperatures using analytical models for phonon, ionized impurity, charged dislocation, surface/interface roughness, and electrolyte-induced scattering. The mobility maximum is thus understood to arise from competition between charged impurity/dislocation scattering and electrolyte scattering. The gate-voltage-induced mobility enhancement is found as large as 2000%, realizing 300 K mobility up to 140 cm2 V-1 s-1. This work thus significantly advances the understanding of mobility-limiting scattering processes in BaSnO3, resulting in outstanding room temperature mobilities.
Bibliographical noteFunding Information:
This work was primarily supported by the National Science Foundation (NSF) through the University of Minnesota (UMN) MRSEC under Grant No. DMR-1420013. Parts of this work were carried out at the Characterization Facility, UMN, which receives partial support from the NSF through the MRSEC program. Portions of this work were also conducted at the Minnesota Nano Center, which is supported by the NSF through the National Nano Coordinated Infrastructure Network, under Grant No. NNCI-1542202. The authors acknowledge H. Yun for STEM imaging and B. Shklovskii for illuminating discussions.
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Data for "Scattering mechanisms and mobility enhancement in epitaxial BaSnO3thin films probed via electrolyte gating"
Wang, H., Prakash, A., Reich, K., Ganguly, K. & Leighton, C., Data Repository for the University of Minnesota, Aug 5 2020