沉积温度对磁控溅射BiFeO3薄膜结构和性能的影响

Effect of Deposition Temperature on the Structural and Physical Properties of BiFeO_3 Films Prepared by Magnetron Sputtering

应用磁控溅射法在以SrRuO3(SRO)薄膜为缓冲层的Pt/TiO2/SiO2/Si(001)基片上制备了多晶BiFeO3(BFO)薄膜,构架了SRO/BFO/SRO异质结电容器。采用X射线衍射、铁电测试仪等研究沉积温度对BFO薄膜结构和性能的影响。X射线衍射图谱显示BFO薄膜为多晶结构。在2.5 kHz测试频率下,500℃生长的BFO薄膜呈现比较饱和的电滞回线,2Pr为145μC/cm2,矫顽场Ec为158 kV/cm,漏电流密度约为2.4×10-4A/cm2。漏电机制研究表明,在低电场区,SRO/BFO/SRO电容器满足欧姆导电机制,在高电场区,满足普尔-弗兰克导电机理。实验发现:SRO/BFO/SRO电容器经过109翻转后仍具有良好的抗疲劳特性。

SrRuO3（SRO）/BiFeO3（BFO）/SRO heterostructure capacitors were fabricated on Pt/TiO2/SiO2/Si（001） substrate using SRO as buffer layer,in which BFO thin films was deposited by RF magnetron sputtering.The effect of deposition temperature on the structural and physical properties of BFO thin film was investigated by X-ray diffraction（XRD） and a ferroelectric tester.X-ray diffraction（XRD） revealed that the BFO thin films were polycrystalline.Under the test frequency of 2.5 kHz,the BFO ferroelectric film deposited at 500 ℃ presented a good saturated hysteresis loop,and the remnant polarization 2Pr,coercive field Ec and leakage current of the 500 ℃ grown BFO film were 145 μC/cm2,158 kV/cm,and 2.4×10-4A/cm2,respectively.The leakage conduction mechanism of the SRO/BFO/SRO capacitor satisfied the ohmic conduction behavior at low applied fields and bulk-limited space-charge-limited conduction（SCLC） at the high applied fields.Moreover,it was found that BFO capacitor possessed very good fatigue-resistance up to 109 cycles.