EFFECTS OF INTERFACIAL STATES ON ELECTRICAL PROPERTIES OF SrBi2Ta2O9 THIN FILMS

Electrical properties of SrBi2Ta2O9 thin-film capacitors with Pt electrodes were characterized immediately and 24 h after top electrode annealing. The leakage current density decreased abruptly 24 h after annealing, whereas it was very high, over 10-4 A/cm2 at 3 V, immediately after annealing. The dielectric dispersion was observed immediately after annealing and became weaker with increasing stabilization time (the sustaining time in air after annealing is finished). Interface resistance increased and the quantity of metallic Bi at the interface decreased with increasing stabilization time. This suggests that conducting phases may be transformed into resistive phases due to the interaction of Bi and O atoms. The imprint of SBT capacitors was strongly dependent upon the initial poled state. The imprint property was improved as stabilization proceeded and this may be due to the relative reduction of electronic carriers participating in the trapping/detrapping. 15 refs.