Energy level alignment and electric and dielectric properties of BST with ITO electrodes

The interface formation of (Ba,Sr)TiO3 thin films and magnetron sputtering SrTiO3 single crystal with transparent conducting Sn-doped indium oxide (ITO) have been studied by photoelectron spectroscopy with in situ sample preparation via RF. The energy level alignment indicates a very small barrier height at the ITO/BST and STO/ITO interfaces. Current-voltage and dielectric measurements have been performed on BST thin films with parallel-plate structure using Pt and ITO for both top and bottom electrodes. A strong influence of electrode materials on electrical and dielectric properties of the BST films is observed. BST capacitors with Pt electrodes show a back-to-back diode behavior and a relatively low leakage current and high dielectric constant. In contrast, the BST films with ITO electrodes show high leakage currents and high dielectric losses.