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

Dielectric relaxation and steady-state leakage currents were studied over a range of bias voltages for Pt-electroded capacitors in which the 50-nm-thi ck (Ba, Sr)TiO3 dielectric layer was sputter deposited at 480 degreesC. A p ronounced 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 = J(0)t(-n)) for intervals of 3-200 s dur ation after application of a voltage step. The relaxation current density w as found to depend linearly on electric field for fields up to 700 kV/cm an d nonlinearly at higher fields. In addition to the Curie-von Schweidler rel axation currents, a time-dependent leakage current was detected under high voltage bias conditions. An empirical model developed to describe leakage c urrents in these films is presented. (C) 2001 American Institute of Physics .