Effect of Growth Induced (Non)Stoichiometry on Interfacial Conductance in ${\mathrm{LaAlO}}_3/{\mathrm{SrTiO}}_3$

We demonstrate a link between the growth process, the stoichiometry of ${\mathrm{LaAlO}}_3$, and the interfacial electrical properties of ${\mathrm{LaAlO}}_3/{\mathrm{SrTiO}}_3$ heterointerfaces. Varying the relative La:Al cation stoichiometry by a few atomic percent in films grown at $1\times {10}^{-3}\mathrm{Torr}$ 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.