La-doped effect on the ferroelectric properties of Bi₄Ti₃O₁₂-SrBi₄Ti₄O[sub 15] thin film fabricated by pulsed laser deposition

Abstract

Bi₄Ti₃O₁₂-SrBi₄Ti₄O[sub 15] (BT-SBTi) thin film was fabricated successfully on Pt/TiO₂/SiO₂/Si(110) substrates by the pulsed laser deposition technique. Films annealed at 650 °C by the rapid temperature process (RTP) have P[sub r]= 12 µC/cm² . But, the fatigue behavior has been observed although no obvious decrease in P[sub r] up to 10[sup 5] s retained time in the BT-SBTi capacitor. After being La doped, the Bi[sub 3.25]La[sub 0.75]Ti₃O₁₂-SrBi₄Ti₄O[sub 15] (BLT-SBTi) has fatigue free properties. P[sub r]= 13.5 µC/cm² was measured in a BLT-SBTi film of 300 nm thickness. It did not show any significant fatigue up to 10[sup 10] switching cycles above the applied field of 250 kV/cm. It also has good retention properties. The field dependence of fatigue behavior and La-doped effect are discussed.