Giant conductivity switching of LaAlO3/SrTiO3 heterointerfaces governed by surface protonation

• Published in: Nature communications Vol. 7; no. 1; p. 10681
• Main Authors: Brown, Keith A., He, Shu, Eichelsdoerfer, Daniel J., Huang, Mengchen, Levy, Ishan, Lee, Hyungwoo, Ryu, Sangwoo, Irvin, Patrick, Mendez-Arroyo, Jose, Eom, Chang-Beom, Mirkin, Chad A., Levy, Jeremy
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10-02-2016; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/119/544; 639/301/119/995; Electrons; Humanities and Social Sciences; Interfaces; multidisciplinary; Science; Science (multidisciplinary); Solvents; Surface chemistry; United States > US; Pittsburgh Pennsylvania; Pennsylvania
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms10681

Complex-oxide interfaces host a diversity of phenomena not present in traditional semiconductor heterostructures. Despite intense interest, many basic questions remain about the mechanisms that give rise to interfacial conductivity and the role of surface chemistry in dictating these properties. Here we demonstrate a fully reversible >4 order of magnitude conductance change at LaAlO
3
/SrTiO
3
(LAO/STO) interfaces, regulated by LAO surface protonation. Nominally conductive interfaces are rendered insulating by solvent immersion, which deprotonates the hydroxylated LAO surface; interface conductivity is restored by exposure to light, which induces reprotonation via photocatalytic oxidation of adsorbed water. The proposed mechanisms are supported by a coordinated series of electrical measurements, optical/solvent exposures, and X-ray photoelectron spectroscopy. This intimate connection between LAO surface chemistry and LAO/STO interface physics bears far-reaching implications for reconfigurable oxide nanoelectronics and raises the possibility of novel applications in which electronic properties of these materials can be locally tuned using synthetic chemistry.
The interface between two oxide materials can play host to numerous exotic phenomenon. Here, the authors observe a four order of magnitude change in the conductance at a lanthanum-aluminate–strontium-titanate interface controlled by surface protonation, which can be reversed by exposure to light.