Study of leakage current in metal–insulator–metal Mg–Al co-doped barium strontium titanate thin films as a function of temperature and applied field

This study investigated the electrical properties of Mg–Al co-doped Ba0.5Sr0.5TiO3 (BSTMA) films, fabricated on a P-type Si (100) substrate by a sol–gel spin coating process. Pt electrodes were deposited by radio frequency magnetron sputtering to form metal–insulator–metal capacitors. The current–voltage characteristics of the BSTMA films were also studied for various external electric fields and temperatures. Experimental results indicate that the leakage currents of Mg–Al co-doped BST films are lower than those of Mg-doped specimens. The leakage currents of 5 mol% Mg-doped and 5 mol% Mg–5 mol% Al- co-doped BST films are 1.14 × 10− 3 and 1.56 × 10− 5 A/cm2, respectively, at 805.5 kV/cm and 298 K. The current–voltage characteristics are ohmic behavior in the lower field region (E ≤ 32 kV/cm) followed by Schottky emission transport behavior in the higher field region (32 ≤ E ≤ 604 kV/cm). While at high field (E ≥ 604 kV/cm), both the Schottky emission and Poole–Frenkel transport behavior are observed. The Schottky emission barrier height and Poole–Frenkel trap depth level depend on the applied electric field and the temperature at which the measurements are made.