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

We demonstrate a link between the growth process, the stoichiometry of LaAlO₃, and the interfacial electrical properties of LaAlO ₃/SrTiO₃ heterointerfaces. Varying the relative La:Al cation stoichiometry by a few atomic percent in films grown at 1×10 ^-3 Torr results in a 2 and 7 order-of-magnitude change in the 300 and 2 K 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.