退火气压对Bi_(3.25)La_(0.75)Ti_3O_(12)铁电薄膜的微观结构和铁电性能的影响

Effect of annealing pressure on the structure and ferroelectric properties of Bi_(3.25)La_(0.75)Ti_3O_(12) thin films

采用sol-gel法在Pt/TiO2/SiO2/p-Si(100)衬底上制备了Bi3.25La0.75Ti3O12(BLT)铁电薄膜,研究了在750℃时不同退火气压(pO2:10-4—3atm)对薄膜微观结构和电学性能的影响.XRD和拉曼光谱结果表明在10-4和3atm氧气压下退火的薄膜晶化度明显降低.同时,XRD结果反映出10-1atm氧气压下退火的薄膜具有a轴择优取向.FSEM截面形貌显示0.1atm氧气压下退火的薄膜由与a轴取向相对应的柱状晶粒构成,1atm氧气压下退火的薄膜为由随机取向相对应的斜杆状晶粒构成.薄膜的微观结构最终影响了其铁电性能.0.1atm氧气压下退火的薄膜具有最大的剩余极化值(Pr=17.8μC/cm2)和最小的矫顽场强(Ec=73.6kV/cm),以及良好的抗疲劳特性.

The effect of annealing pressure on the structure and ferroelectric properties was investigated for Bi 3.25 La 0.75 Ti3O 12 （BLT） thin film prepared on Pt/TiO2/SiO2/p-Si（100） substrate by sol-gel method. The amorphous film samples were annealed at 750 ℃ for 30 min under oxygen pressures varying from 10^ -4 to 3 atm. Then the structure, crystallization degree, and morphology were characterized by X-ray diffraction （XRD）, Raman spectroscopy, and field-emission scanning electron microscope （FSEM） to clarify the effect of annealing pressure on the structure of the film. The XRD and Raman spectroscopy results showed a clear decreasing of the crystallization degree of the film annealed under oxygen pressures of 10^ -4 and 3 atm. FSEM results showed different growth orientations of grains under different oxygen pressures. The structure of the BLT film was revealed to affect their ferroelectric properties. The largest remanent polarization of 17.8 μC/cm^2 with the coercive field of 73.6 kV/cm and good fatigue property were obtained for the film annealed under oxygen pressure of 0.1 atm.