Physical characteristics and electrical properties of Sr0.8Bi2+xTa2O9 films on Al2O3/Si annealed at high temperature

Bismuth-containing layered perovskite Sr0.8Bi2+xTa2O9 (SBT) thin films with x=0-0.8 were prepared to investigate annealing temperature effect, especially at high temperature, on physical characteristics and electrical properties of SBT films on Al2O3 (10 nm)/Si. At 800 degreesC, the Sr0.8Bi2Ta2+xO9/Al2O3/Si exhibits ferroelectric mode and the width of memory window decreases with the increase of Bi content that is dependent on the effective coercive field. However, at a higher annealing temperature of 900 degreesC, a larger ferroelectric memory window was obtained for Bi-rich Sr0.8Bi2+xTa2O9 (x=0.4 or 0.8) films compared to SBT film (x=0) that should be related to the reduced leakage current due to the formation of rod-shape grains and amorphous SBT composite layer. The leakage current of Sr0.8Bi2.4Ta2O9/Al2O3/Si annealed at 900 degreesC is about 1.2x10(-9) A/cm(2) that has two orders of magnitude lower than that of 800 degreesC-annealed SBT films measured at -100 kV/cm. However, the Sr0.8Bi2Ta2O9 (x=0) film on Al2O3/Si capacitor shows no obvious change with the increase of annealing temperature. (C) 2003 American Institute of Physics.