Dielectric relaxation and steady-state leakage in low-temperature sputtered (Ba, Sr)TiO3 thin films

Abstract

Dielectric relaxation and steady-state leakage currents were studied over a range of bias voltages for Pt-electroded capacitors in which the 50-nm-thick (Ba, Sr)TiO3 dielectric layer was sputter deposited at 480 °C. A pronounced polarity dependence in the current–voltage characteristic of the capacitors was observed. Dielectric relaxation in the films showed a Curie–von Schweidler time dependence (J=J0t−n) for intervals of 3–200 s duration after application of a voltage step. The relaxation current density was found to depend linearly on electric field for fields up to 700 kV/cm and nonlinearly at higher fields. In addition to the Curie–von Schweidler relaxation currents, a time-dependent leakage current was detected under high voltage bias conditions. An empirical model developed to describe leakage currents in these films is presented.