Leakage mechanism of (Ba0.7Sr0.3)TiO3 thin films in the low-temperature range

Abstract

$\mathrm{Pt}\mathrm{/(}{\mathrm{Ba}}_{\text{0.7}}{\mathrm{Sr}}_{\text{0.3}}){\mathrm{TiO}}_3(\mathrm{BST}\mathrm{)/}{\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{\text{7−x}}(\mathrm{YBCO})$ capacitors on ${\mathrm{SrTiO}}_3$ substrates were fabricated, and the temperature dependence of their current–voltage characteristics was studied in the temperature range from 100 to 300 K. It was found that the leakage current strongly depends on the voltage polarity and temperature. In the case of a Pt electrode negatively biased at a high electric field (>400 kV/cm), the Pt/BST interface acts as a Schottky barrier with the barrier height of 0.47 eV in the temperature range from 200 to 300 K. When the YBCO electrode was biased negatively and the electrical field was maintained higher than 64 kV/cm, the leakage mechanism shows space-charge-limited-current behavior.