Interface behavior in La$_{\mathrm{1-x}}$Sr$_{\mathrm{x}}$FeO$_{3-\delta}$ /Nb:SrTiO$_{3}$ perovskite oxide heterostructures

We report the interfacial transport behavior in La$_{\mathrm{1-x}}$Sr$_{\mathrm{x}}$FeO$_{3-\delta}$ /Nb:SrTiO$_{\mathrm{3}}$ perovskite oxide heterostructures. Strained epitaxial films were deposited on SrTiO$_{3}$ and Nb:SrTiO$_{3}$ substrates using oxide molecular beam epitaxy. Oxygen concentration was controlled by heating and re-annealing in a tube furnace with a mixture of O$_{2}$ and O$_{3}$. Temperature dependent current-voltage (I-V) characteristics were measured from the junctions. From these I-V data, ideality factors for the heterojunctions were obtained. The ideality factors are found to be much larger than 1, indicating transport differs substantially compared to conventional semiconductor heterostructures.