Effect of Bi2O3 seed layer on crystalline orientation and ferroelectric properties of Bi3.25La0.75Ti3O12 thin films prepared by rf-magnetron sputtering method

Bi 3.25 La 0.75 Ti 3 O 12 (BLT) thin films with Bi2O3 seed layers were prepared on Pt(111)/Ti/SiO2/Si substrate by rf-magnetron sputtering method. The effect of annealing procedure, thickness, and position of Bi2O3 seed layer on the structural and electrical properties of BLT thin film was investigated. When using a two-step annealing procedure, the x-ray diffraction pattern indicated that BLT thin film with a Bi2O3 seed layer showed c-axis preference orientation. Compared with Pt/BLT/Bi2O3/Pt structure film, the Pt/Bi2O3/BLT/Bi2O3/Pt structure film showed higher oriented to c direction. The ferroelectric property of BLT thin film improved remarkably with the incorporation of Bi2O3 seed layer. Under the applied voltage of 14 V, the remnant polarization and coercive voltage of the Bi2O3/BLT/Bi2O3 capacitor with 18-nm-thick Bi2O3 seed layer were 45.2 μC/cm2 and 9.2 V, respectively. Moreover, the Pt/Bi2O3/BLT/Bi2O3/Pt film with 18-nm-thick Bi2O3 seed layers exhibited good fatigue endurance even after 6×109 switching cycles, which was attributed to the double-sided Bi2O3 layer. They decreased the grain boundary density by enhancing the grain size of BLT film and enhanced the c-axis preferential orientation. Compared with BLT film deposited directly on Pt, double-sided Bi2O3 layer would greatly enhance the leakage current resistance of the BLT film.