Metal electrodes are a universal element of all electronic devices. Conducting SrRuO3 (SRO) epitaxial thin films have been extensively used as electrodes in complex-oxide heterostructures due to good lattice mismatches with perovskite substrates. However, when compared to SRO single crystals, SRO thin films have shown reduced conductivity and Curie temperatures (TC), which can lead to higher Joule heating and energy loss in the devices. Here, we report that high-quality SRO thin films can be synthesized by controlling the plume dynamics and growth rate of pulsed laser epitaxy (PLE) with real-time optical spectroscopic monitoring. The SRO thin films grown under the kinetically controlled conditions, down to ca. 16 nm in thickness, exhibit both enhanced conductivity and TC as compared to bulk values, due to their improved stoichiometry and a strain-mediated increase of the bandwidth of Ru 4d electrons. This result provides a direction for enhancing the physical properties of PLE-grown thin films and paves a way to improved device applications.
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We acknowledge the support of the National Science Foundation Grant No. DMR-1454200 for the sample syntheses and characterizations. S.R. and M.J.H. were supported by the Basic Science Research Program through NRF (2014R1A1A2057202), and the computing resource is supported by KISTI (KSC-2014-C2-046). The XRD measurements performed at ORNL were supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division.
See supplementary material for the results of atomic force microscopy, first-principles calculations, XRD RSM, and additional transport measurements.
Thompson, Justin K.; Nichols, J.; Lee, S.; Ryee, S.; Gruenewald, John H.; Connell, John G.; Souri, Maryam; Johnson, J. M.; Hwang, J.; Han, M. J.; Lee, H. N.; Kim, D. -W.; and Seo, Sung S. Ambrose, "Enhanced Metallic Properties of SrRuO3 Thin Films via Kinetically Controlled Pulsed Laser Epitaxy" (2016). Physics and Astronomy Faculty Publications. 478.