Novel Candidate of c-axis-oriented BLSF Thin Films for High-Capacitance Condenser

摘要

c-axis-oriented SrBi_2Ta_2O_9 thin films with various thickness ranging from 20-170 nm were epitaxially grown on (100)SrRuO_3 (SrRuO_3 is give for the pseudo-cubic unit cell)//(100)SrTiO_3 substrates by metalorganic chemical vapor deposition (MOCVD). The relative dielectric constants of these films kept a constant value of about 55 with decreasing film thickness down to 20 nm. The capacitances of these films were almost independent of the applied electric field; change of capacitance for these films on applied electric field from 0 kV/cm to 100 kV/cm was within 0.017 % and tanδ value was within 1.3 %. The leakage current densities were constant against the film thickness on the order of 10~(-8) A/cm~2 at 150 kV/cm. Surface flatness of these films were also almost the same irrespective of the film thickness. These characteristics are very attractive for high-capacitance condenser application. Therefore, c-axis-oriented BLSF thin films are novel candidates for high-capacitance condenser application having both bias-free and thickness independent characteristics together with the good surface smoothness.