Effect of growth induced (non)stoichiometry on interfacial conductance in LaAlO₃/SrTiO₃

E. Breckenfeld, N. Bronn, J. Karthik, A. R. Damodaran, S. Lee, N. Mason, and L. W. Martin

Accepted Monday Apr 1, 2013

We demonstrate a link between the growth process, the stoichiometry of LaAlO3, and the interfacial electrical properties of LaAlO3/SrTiO3 heterointerfaces. Varying the relative La:Al cation stoichiometry by a few atomic percent in films grown at 1x10-3 Torr results in a two and seven order-of-magnitude change in the 300K and 2K sheet resistance, respectively, with highly conducting states occurring only in La-deficient or Al-excess films. Further reducing the growth pressure results in an increase of the carrier density and a dramatic change in mobility. We discuss the relative contributions of intrinsic and extrinsic effects in controlling the physical properties of this widely studied system.