Surface charges {\&} adsorbates tune the electron gas at the LaAlO$_{3}$/SrTiO$_{3 }$interface

ORAL

Abstract

The physical properties of the LaAlO$_{3}$/SrTiO$_{3}$ heterointerface are substantially determined by the density and mobility of the electron gas at the buried interface. Here, we present two ways to tune the electron gas from the LaAlO$_{3}$ surface. First, the electron gas can be locally tuned by using biased atomic force microscope probe [1]. Our studies show that this is caused by the accumulation of charge on the LaAlO$_{3}$ surface [2], and can change the density by up to 3$\times $10$^{13}$ cm$^{-2}$[3], comparable to the maximum modulation achieved in normal field effect devices. Second, we found that the electron gas can be dramatically tuned by the surface adsorption of common polar solvents such as acetone, ethanol and water [4]. This strong surface-interface coupling provides a new technique for manipulating the interface-confined electrons. Most significantly, adsorbates induce an insulator to metal transition when the thickness of the LaAlO$_{3}$ is 3 unit cells, suggesting sensor applications with extremely large sensitivity. \\[4pt] [1] C. Cen \textit{et al.}, \textit{Nature Mater. }\textbf{7}, 298 (2008). \\[0pt] [2] Y. Xie \textit{et al.}, \textit{Nano Lett.} \textbf{10}, 2588 (2010). \\[0pt] [3] Y. Xie \textit{et al.}, \textit{Adv. Mater.} \textbf{23}, 1744(2011). \\[0pt] [4] Y. Xie \textit{et al.}, \textit{Nature Commun.} \textbf{2}, 494 (2011).

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Authors

  • Yanwu Xie

    Department of Applied Physics and Stanford Institute for Materials and Energy Science, Stanford University,Stanford, California 94305, USA

  • Chris Bell

    Department of Applied Physics and Stanford Institute for Materials and Energy Science, Stanford University,Stanford, California 94305, USA, Stanford University, USA, Stanford Institute for Materials and Energy Sciences, Stanford University, Stanford Univeristy

  • Yasuyuki Hikita

    Department of Applied Physics and Stanford Institute for Materials and Energy Science, Stanford University,Stanford, California 94305, USA, Stanford Institute for Materials and Energy Sciences, Stanford University

  • Harold Hwang

    Department of Applied Physics and Stanford Institute for Materials and Energy Science, Stanford University,Stanford, California 94305, USA, Stanford University, USA, Stanford Institute for Materials and Energy Sciences, Stanford University, Stanford University, Stanford University and SLAC National Accelerator Laboratory