The Effect of La Concentration on the Properties of PLT Thin Films: From the Perspective of DRAM Applications

초록

We have studied the effects of La concentration on the dielectric and ferroelectric properties of lead lanthanum titanate (PLT) thin films by using sol-gel method. Both the dielectric and ferroelectric properties were greatly affected by the La concentration. The dielectric constants of the films varied from 340 to 870 with varying La concentration in the range from 15 to 33mol%. Hysteresis loop became slimmer with the increase of La concentration from 15 to 28mol% and a little fatter again with the increase of La concentration from 28 to 33mol%. Among the films investigated in this research, PLT(28) thin film showed the best dielectric properties for the application to the dielectrics of ULSI DRAM's. At the frequency of 100Hz, the dielectric constant and the loss tangent of PLT(28) thin film were 940 and 0.08, respectively. Its leakage current density at 1.5X105 V/cm was 1X10-6 A/cm2. The comparison between the simulated and the experimental curves for the switching transient characteristics showed that PLT(28) thin film behaved like normal dielectrics