FERROELECTRIC PROPERTIES AND CURRENT CONDUCITON MECHANISMS OF Pt/(Bi,La)_4Ti_3O_(12)/Pt CAPACITORS

摘要

We studied the ferroelectric properties and current conduction characteristics of (Bi,La)_4Ti_3O_(12) (BLT) thin films. Random oriented BLT thin films were prepared on Pt/IrO_x/Ir structure by MOD (metal-organic decomposition), and crystallized by RTA (rapid thermal annealing) and the subsequent furnace annealing process. The swichable polarization (P-P) and coercive voltage (2Vc) of BLT thin films were 20.1 mu C/cm~2 and 1.8V at 3V driving voltage. The leakage current density (J_L) with bias polarity was 4.0E-7 A/cm~2 under positive and 9.7E-7 A/cm~2 under negative, respectively. The leakage current characteristics of BLT films on Pt/IrO_x/Ir electrode were controlled by the modified Schottky emission, because the field emission of BLT capacitors are quite dependent upon temperature and the measured data are well straightly fitted in log(J/E) vs E~(1/2) plots. This result is shown to combine interface and bulk controlled conduction properties. The barrier height (PHI_B) of the Pt/BLT/Pt was calculated as 0.53 eV by temperature-dependent current-voltage measurements.